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  1. Ontogeny of Themeda triandra tillers in the false thornveld of the eastern cape

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa • Authors: J.E. Danckwerts --- Department of Agriculture (Eastern Cape Region), A.J. Aucamp --- Department of Agriculture (Eastern Cape Region), L.P. Du Toit --- Department of Agriculture (Eastern Cape Region),
    Marked populations of Themeda triandra tillers were sequentially sampled at fortnightly intervals under normal conditions and without moisture stress respectively, covering a period from tiller initiation through to senescence after flowering. Parameters recorded were height of shoot apex, tiller mass,...
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  2. Acidity/Al aspects in soils of the Lusikisiki area, Eastern Cape Province

    Acidity/Al aspects in soils of the Lusikisiki area, Eastern Cape Province

    Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: C. Bühmann --- , D.J. Beukes --- , D.P. Turner --- ,
    Soil acidity related parameters like pH, extractable and soil organic matter bound Al, amorphous Al phases and Al substitutions in secondary iron minerals were determined on 57 samples from 15 representative soil profiles from the Lusikisiki area. The pH (H2O)...
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  3. Thin subspaces of <em>L</em> <sup>1</sup>(λ)

    Thin subspaces of L 1(λ)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: R. Anantharaman --- ,
    Let (S,Σ, λ) be a finite positive measure space. In their extension of Liapunov's theorem to infinite dimensions, Kingman and Robertson (in 1968) defined a subset N of the real L 1(λ) to be thin if for every A ∈...
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  4. Multiple strategies for resilient livelihoods in communal areas of South Africa

    Multiple strategies for resilient livelihoods in communal areas of South Africa

    Item type: Journal Article • Journal: African Journal of Range & Forage Science • Authors: Wayne Twine --- School of Animal, Plant and Environmental Sciences, South Africa
    Livestock farming in communal areas is an activity pursued by rural households as one of a range of livelihood strategies aimed at spreading risk. The cash and non-cash benefits derived from livestock, as well as the wide range of secondary...
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  5. Calibration of a hand-held instrument for measuring condensed tannin concentration based on UV- and red-excited fluorescence

    Calibration of a hand-held instrument for measuring condensed tannin concentration based on UV- and red-excited fluorescence

    Item type: Journal Article • Journal: African Journal of Range & Forage Science • Authors: Peter Scogings --- Department of Agriculture, South Africa Sithembile Siko --- Department of Agriculture, South Africa Robert Taylor --- NRF/SAEON Ndlovo Node, South Africa
    Condensed tannins are ecologically important compounds in plants for several reasons, e.g. as herbivore deterrents or protecting photosynthetic tissues against ultraviolet radiation. The hand-held Dualex Series 4 instrument was originally developed for indirect determination of flavonol concentrations in crops. Flavonols...
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  6. Provincial road condition and round wood timber transport in South Africa

    Provincial road condition and round wood timber transport in South Africa

    Item type: Journal Article • Journal: The Southern African Forestry Journal • Authors: StephenJ. Nicholls ReinoE. Pulkki PierreA. Ackerman
    The context of the study is the concern over declining provincial road conditions due to insufficient government funding for road maintenance. The roads are used by a wide variety of commercial and private interests that contribute a broad range of...
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  7. Threats to Enabling Contexts: Exploring Adolescents' Experiences of Aggression

    Threats to Enabling Contexts: Exploring Adolescents' Experiences of Aggression

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Quintin Ludick --- North-West University, Vera Roos --- North-West University,
    This article explores adolescents' experiences of aggression in a secondary, multi-cultural school context in South Africa. The study group comprised of boys (n=24) and girls (n=17), attending grades 8–12. An inductive qualitative research approach was chosen where participants wrote about...
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  8. The Challenges of HIV/AIDS Counselling in Nigerian Secondary Schools: A Case Study of Kwara State

    The Challenges of HIV/AIDS Counselling in Nigerian Secondary Schools: A Case Study of Kwara State

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Lasiele Alabi Yahaya --- University of Ilorin,
    The study investigated the challenges of HIV/AIDS counselling in Nigerian secondary schools as expressed by school counsellors in Kwara state, Nigeria. The respondents comprised 132 purposively selected counsellors in Kwara state public secondary schools (Male=85; Female=47). Data were collected with...
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  9. Child Physical Abuse Among Urban Secondary School Pupils in Zimbabwe

    Child Physical Abuse Among Urban Secondary School Pupils in Zimbabwe

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Pesanayi Gwirayi --- University of Fort Hare, South Africa Almon Shumba --- University of Fort Hare, South Africa
    The study had two main objectives: (a) to examine the nature and prevalence of child physical abuse among urban secondary school pupils in Zimbabwe; and (b) to investigate pupils' views on the causes of child physical abuse among urban secondary...
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  10. Teachers' Experience of Aggression in a Secondary School: Case study

    Teachers' Experience of Aggression in a Secondary School: Case study

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Hester Steyn --- University of Johannesburg, South Africa Chris Myburgh --- University of Johannesburg, South Africa Marie Poggenpoel --- University of Johannesburg, South Africa
    The study explored and described the experience of aggression on teachers by students in a secondary school. Participants were a purposive sample of 8 (males = 3, females = 5, language group= Afrikaans and English, range in years of experience...
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  11. Influences on Fertility Control and Early Parenthood in a Rural District of Zimbabwe

    Influences on Fertility Control and Early Parenthood in a Rural District of Zimbabwe

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Nyengeterai Chemhuru --- Zimbabwe Open University, Zimbabwe Jephias Matunhu --- Midlands State University, Zimbabwe Almon Shumba --- Central University of Technology, South Africa Winifrida S. Nyamande --- Zimbabwe Open University, Zimbabwe Janet P. Mahlatini --- Zimbabwe Open University, Zimbabwe
    This study investigated influences on fertility control and early parenthood among teenage learners from a rural district in Zimbabwe. Data on perceived influences on risks for early parenthood were collected from 1320 female secondary school learners (mean age=16 years, SD=1.35)...
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  12. Peer Aggression by Secondary School Learners in a South African School Setting: Effects of Race, Ethnicity, and Gender

    Peer Aggression by Secondary School Learners in a South African School Setting: Effects of Race, Ethnicity, and Gender

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Johan Botha --- North West University, South Africa Chris Myburgh --- University of Johannesburg, South Africa Marie Poggenpoel --- University of Johannesburg, South Africa
    This study reports the experience of aggression by secondary school learners attending a South African school. There were 14 participants ranging in age from 16 to 19 years (Gender: 6 young women and 8 young men; Ethnicity: 7 Black; 3...
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  13. Group Polarization Effects on Decisions by Selected Kenyan Secondary School Disciplinary Panels

    Group Polarization Effects on Decisions by Selected Kenyan Secondary School Disciplinary Panels

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Peter J. O. Aloka --- Catholic University of Eastern Africa, Olaniyi Bojuwoye --- University of the Western Cape,
    This study investigated social group phenomenon of group polarization effects on disciplinary hearing decisions in selected Kenyan secondary school. The participants were 78 school personnel (females = 42 % and males 58%) from ten secondary schools with both unisex (n...
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  14. SHEAVES OF BANACH SPEACES

    SHEAVES OF BANACH SPEACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: B. Banaschewski --- Department of Mathematics, Canada
    This paper presents a number of results concerning sheaves on a topological space, with values in the category BAN of Banach spaces, over K = R or Ø, and linear contractions. After showing that these sheaves are reflective in the...
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  15. ON CERTAIN FACTORIZATIONS OF FUNCTORS INTO THE CATEGORY OF QUASI-UNIFORM SPACES

    ON CERTAIN FACTORIZATIONS OF FUNCTORS INTO THE CATEGORY OF QUASI-UNIFORM SPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: G. C.L. Brümmer --- ,
    This paper is motivated by the search for natural extensions of classical uniform space results to quasi-uniform spaces. As instances of such extensions we restate some theorems of P. Fletcher and W.F. Lindgren [Pacific J. Math. 43 (1971), 619–6311 on...
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  16. HYPERSPACES

    HYPERSPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A.G. Hitchcock --- Mathematics Department, Rhodesia
    In this paper we survey the theory of some of the structures that have been defined on sets of subsets, and illustrate the way motivation has come from functional analysis; we show how certain results can be generalized in the...
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  17. A NOTION OF COMPLETENESS OF TOPOLOGICAL STRUCTURES

    A NOTION OF COMPLETENESS OF TOPOLOGICAL STRUCTURES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Kazumi Nakano --- Department of Mathematics, U.S.A.
    A connector U on a space S is a function from S to the power set of S such that each x in s belongs to its image. The image of x is denoted by xU. In other words, the...
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  18. CARTESIAN CLOSED COREFLECTIVE HULLS

    CARTESIAN CLOSED COREFLECTIVE HULLS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: L.D. Nel --- , Canada
    Conditions are established under which a given class of objects in a topological category will have a Cartesian closed coreflective hull. The main theorem is used to discover new Cartesian closed topological categories and to unify a diversity of known...
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  19. CATEGORIES OF TOPOLOGICAL GROUPS

    CATEGORIES OF TOPOLOGICAL GROUPS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: BarbaraV.Smith Thomas --- Department of Mathematical Sciences, Tennessee
    This paper is a survey of recent (and some not so recent, results concerning categorical constructions on topological groups, with particular emphasis on free topological groups and coproducts (free products) of topological groups. An extensive bibliography is included.
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  20. GRAPHIC EXTENSIONS OF MAPPINGS

    GRAPHIC EXTENSIONS OF MAPPINGS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: F.A. Delahan --- , USA G.E. Strecker --- , USA
    Given a mapping f: X → Y and an extension e: X → [Xtilde] of X, the restriction of the projection Π: [Xtilde] X Y → Y to the closure of the graph of f in [Xtilde] X Y is...
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  21. CATEGORICAL HOMOTOPY

    CATEGORICAL HOMOTOPY

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Georges Hoff --- Département de Mathématiques,
    We present a homotopy theory of small categories. In a work of this nature there is a need to give a theory which is clear and which shows the methods of work in this field. It is also necessary to...
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  22. PRODUCTS OF DIFFERENTIAL EXPRESSIONS WITHOUT SMOOTHNESS ASSUMPTIONS

    PRODUCTS OF DIFFERENTIAL EXPRESSIONS WITHOUT SMOOTHNESS ASSUMPTIONS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: W.N. Everitt --- Department of Mathematics, Scotland, U.K. A. Zettl --- Department of Mathematical Sciences,
    To form products of differential expressions in the classical way it is necessary to place heavy differentiability assumptions on the coefficients. Here we consider symmetric (formally self-adjoint) expressions defined, not in the classical way, but in terms of quasi-derivatives. With...
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  23. HAUSDORFF NEARNESS SPACES

    HAUSDORFF NEARNESS SPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: N.C. Heldermann --- ,
    A categorical characterization of the category Haus of Hausdorft topological spaces within the category Top of topological spaces is given. A notion of a Hausdorff nearness space is then introduced and it is proved that the resulting subcategory Haus Near...
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  24. WHEN ARE DIVISIBLE ABELIAN GROUPS INJECTIVE?

    WHEN ARE DIVISIBLE ABELIAN GROUPS INJECTIVE?

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: B. Banaschewski --- Department of Mathematical Sciences McMaster, Canada
    The above question is considered, in the categories ShL of sheaves on a local lattice L and MEns of sets acted upon by a monoid M, for either all divisible abelian groups or all torsionfree divisible abelian groups, the aim...
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  25. COREFLECTIONS INDUCED BY FINE FUNCTORS

    COREFLECTIONS INDUCED BY FINE FUNCTORS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: N.C. Heldermann --- ,
    In 1974 A. W. Hager initiated the study of metric-fine uniform spaces. It was observed that the definition of metric-fine spaces relied on the class M of metric uniform spaces and the fine functor α, which reequips every uniform space...
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  26. BIFRAMES AND BISPACES

    BIFRAMES AND BISPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: B. Banaschewski --- Banaschewski Department of Mathematical Sciences McMaster, Canada G. C.L. Brümmer --- Department of Mathematics, K.A. Hardie --- Department of Mathematics,
    The concept of a biframe is introduced. Then the known dual adjunction between topological spaces and frames (i.e. local lattices) is extended to one between bispaces (i.e. bitopological spaces) and biframes. The largest duality contained in this dual adjunction defines...
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  27. REAL COMPACTIFICATIONS THROUGH ZERO-SET SPACES

    REAL COMPACTIFICATIONS THROUGH ZERO-SET SPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Christopher R.A. Gilmour --- Department of Mathematics,
    The Alexandroff (= zero-set) spaces were introduced in [l] as the “completely normal spaces”, and have been studied in a number of more recent papers. In this paper we unify the theory of Wallman realcompactifications via the Alexandroff bases and...
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  28. ON EPIDENSE SUBCATEGORIES OF TOPOLOGICAL CATEGORIES

    ON EPIDENSE SUBCATEGORIES OF TOPOLOGICAL CATEGORIES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Eraldo Giuli --- , Italy Anna Tozzi --- , Italy
    Dense subcategories were introduced by S. Mardešić for an inverse system approach to (categorical) shape theory.
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  29. EXPONENTIAL LAWS FOR ORDERED “TOPOLOGICAL” VECTOR SPACES

    EXPONENTIAL LAWS FOR ORDERED “TOPOLOGICAL” VECTOR SPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Kyung Chan Min --- Department of Mathematics and Statistics, Canada
    The category of X-decomposable ordered vector spaces over a convenient category X is introduced and it is shown to uphold an exponential law [E8F,G] = [E,[F, G]] and to have limits and colimits. As the main special cases of X,...
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  30. FAITHFULNESS VS. TOPOLOGICITY

    FAITHFULNESS VS. TOPOLOGICITY

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: G.E. Strecker --- Dept. of Mathematics Kansas State, U.S.A. T. Titcomb --- , U.S.A.
    The fact that faithful functors are intimately connected with functors of topological type has been known for scene time. Here, we make the connection precise by introducing the notion of relatively topological functors, and characterize faithful functors as precisely those...
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  31. DISCRETE UNIFORM STRUCTURES AND QUASITOPOI

    DISCRETE UNIFORM STRUCTURES AND QUASITOPOI

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: MichaelD. Rice --- Department of Mathematics,
    It is known that no non-trivial subcategory of the category of topological spares is a quasitopos in the sense of Penon. The purpose of this note is to establish the existence of a proper class of sub-categories of the category...
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  32. PRME AND k-PRIME IDEALS IN Ω-GROUPS

    PRME AND k-PRIME IDEALS IN Ω-GROUPS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Buys --- Department of Mathematics, South Africa G.K. Gerber --- Department of Mathematics, South Africa
    In this paper we define two concepts of prime ideals for Ω-groups. The first generalizes the definitions of prime ideal in rings, nearrings, Γ-rings, associative algebras and Lie algebras. The second generalizes a concept defined for groups by Ščukin ([21])...
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  33. CARTESIAN CLOSEDNESS AND THE MCNEILLE COMPLETION OF AN INITIALLY STRUCTURED CATEGORY

    CARTESIAN CLOSEDNESS AND THE MCNEILLE COMPLETION OF AN INITIALLY STRUCTURED CATEGORY

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: I.W. Alderton --- Department of Mathematics, South Africa
    An adaptation of a theorem by Herrlich [5] shows that every initially structured category A can be fully embedded in a topological category AC, which is, in fact, a MacNeille completion of A. It is then shown that A is...
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  34. EXPONENTIAL LAW AND θ-CONTINUOUS FUNCTIONS

    EXPONENTIAL LAW AND θ-CONTINUOUS FUNCTIONS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Di Concilio --- , ITALIA
    The category θ-Top of topological spaces and θ-continuous functions is not Cartesian closed; but it is known that under certain local property assumptions, the exponential law in θ-Top is fulfilled. We define a functor from θ-Top to the category of...
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  35. ON A-WEAKLY MPACT OPERATORS

    ON A-WEAKLY MPACT OPERATORS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Teresa Alvarez --- Departamento de Teoria de Funciones Facultad de Ciencias Avda, SPAIN
    The aim of this note is to study the A-weakly compact operators using an arbitrary space ideal A. Since F ⊂ A the n-weakly compact operators of [9] are particular A-weakly compact operators.
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  36. THOUGHTS ON THE CANTOR-BERNSTEIN THEOREM

    THOUGHTS ON THE CANTOR-BERNSTEIN THEOREM

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: B. Banaschewski --- Department of Mathematics and Statistics, Canada G. C.L. Brummer --- Department of Mathematics, South Africa
    The usual proofs of the well-known set-theoretical theorem “Given one-one maps f: A → B and g:B → A, there exists a one-one onto map h:A → B” actually produce a map h:A → B contained in the relation f...
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  37. ON THE IMMEDIATE EXTENSIONS OF A VALUED FIELD

    ON THE IMMEDIATE EXTENSIONS OF A VALUED FIELD

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: BW Green --- Department of Mathematics, Republic of South Africa
    In this paper the topological methods introduced by Kaplansky and the theory of linear compactifications are used to prove a result classifying the maximal immediate extensions of a valued field. Results on the existence of a complete discrete rank n...
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  38. CARTESIAN CLOSED TOPOLOGICAL HULLS AS INJECTIVE HULLS

    CARTESIAN CLOSED TOPOLOGICAL HULLS AS INJECTIVE HULLS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: R. Herrlich --- , Fed. Rep. Germany G.E. Strecker --- Dept. of Mathematics, U.S.A.
    It is shown that (concretely) Cartesian closed topological hulls can be characterized as injective hulls in a rather natural setting. The characterization of locale hulls as injective hulls in the category of (meet-) semilattices by Bruns & Lakser and Born...
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  39. INJECTIVE RESOLVENTS AND PREENVELOPES

    INJECTIVE RESOLVENTS AND PREENVELOPES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Overtoun Jenda --- Department of Mathematics, Botswana
    Let R be a noetherian ring, and denote the full subcategories of R-modules L such that Exti(E,L)=0 for all injective R-modules E for 1⋚i⋚n and O⋚i⋚n by Cn, and C′n respectively. Then LεCn, if and only if every injective resolution...
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  40. BOUNDS FOR INDICES OF NILPOTENCY OF FINITELY GENERATED NIL RINGS OF FINITE INDEX

    BOUNDS FOR INDICES OF NILPOTENCY OF FINITELY GENERATED NIL RINGS OF FINITE INDEX

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: AbrahamA. Klein --- School of Mathematical Sciences, Israel
    An improved bound is given for the index of nil-potency of a finitely generated nil ring of index n in terms of the index of nilpotency of the ideal generated by Tm where m = [n/2] and T is a...
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  41. ON AN ALGEBRAIZATION OF MEASURE THEORY. ABSTRACT SEMIRINGS

    ON AN ALGEBRAIZATION OF MEASURE THEORY. ABSTRACT SEMIRINGS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Teo Sturm --- Department of Mathematics and Applied Mathematics, Republic of South Africa
    The concept of a semiring is introduced as a semilattice analogue of a semiring of sets. A detailed study of its embeddability into r-complete Boolean algebras is carried out. Some of its properties which are important from the standpoint of...
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  42. WALLMAN REMAINDERS OF REGULAR SPACES

    WALLMAN REMAINDERS OF REGULAR SPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: DarrellW. Hajek --- Department of Mathematics,
    This paper shows that the only Hausdorff spaces which can occur as Wallman remainders of Regular spaces are themselves completely regular. This is in contrast to the previously known result that any T1 space can occur as a Wallman remainder.
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  43. A NOTE ON DEFINITE QUADRATIC SPACES AND BAER ORDERINGS

    A NOTE ON DEFINITE QUADRATIC SPACES AND BAER ORDERINGS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Robert Piziak --- Department of Mathematics, U.S.A.
    Let (k,E,Φ) be a definite quadratic space of dimension at least 3. Under certain assumptions, the set {Φ(z,z)|z ≠ in E} is a Baer ordering for k. Under somewhat more restrictive assumptions, the product of positive elements will...
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  44. A NOTE ON GENERALIZED TAUBERIAN OPERATORS

    A NOTE ON GENERALIZED TAUBERIAN OPERATORS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Teresa Alvarez --- Departamento de Teoría de Funciones, SPAIN
    A bounded linear operator T: X → Y (Banach spaces) is Tauberian provided T “x” ε JYY implies x” ε JxX. We use a subspace S(X) of X” such that S(X) replaces the subspace JXX and so we can define...
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  45. SOME CATEGORIES WHICH HAVE NO MINIMAL GENERATING CLASSES

    SOME CATEGORIES WHICH HAVE NO MINIMAL GENERATING CLASSES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: DarrellW. Hajek --- Department of Mathematics,
    A method is introduced or demonstrating that a category has no minimal generating class. This technique is then utilized to show that various categories have no minimal generating classes. These categories include the completely Hausdorff spaces and the regular completely...
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  46. TRANSCENDENTAL AND ALGEBRAIC EXTENSIONS OF COMMUTATIVE RINGS

    TRANSCENDENTAL AND ALGEBRAIC EXTENSIONS OF COMMUTATIVE RINGS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: HJ Schutte --- Department of Mathematics, South Africa
    Transcendental and algebraic elements over commutative rings are defined. Rings with zero nil radical are considered. For a transcendental over R, necessary and sufficient conditions are derived for elements of R[α] to be algebraic or transcendental over R. For R...
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  47. H-ULTRABORNOLOGICAL SPACES

    H-ULTRABORNOLOGICAL SPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Teresa Alvarez --- Depto. Mathematics, Estadistica y Cornputacién Facultad de Ciencias, SPAIN
    In this paper we define a special type of H-locally convex space—H-ultrabornological space -. We shall characterize those H-locally convex spaces in terms of linear maps and of inductive limits.
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  48. A NOTE ON THE FRONT CLOSURE TOPOLOGY

    A NOTE ON THE FRONT CLOSURE TOPOLOGY

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: G. ERVYNCK --- , BELGIUM
    The frontclosure topology is a refinement of the original topology on a space . The former is related to two axioms for the lattice of closed sets. As a result, frontclosure yields a coreflection between two suitable subcategories...
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  49. POWER-OBJECTS IN MONOTOPOLOGICAL CATEGORIES

    POWER-OBJECTS IN MONOTOPOLOGICAL CATEGORIES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: I. Alderton --- Department of Mathematics, Republic of South Africa
    An investigation is made of Cartesian closedness of monotopological categories A which are not necessarily c-categories. Results include: a description of the underlying sets of the power-objects in terms of the horn-sets of a certain monotopological subcategory of A; the...
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  50. A NIL RADICAL FOR Ω-GROUPS

    A NIL RADICAL FOR Ω-GROUPS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: G.K. Gerber --- Dept of Mathematics, South Africa
    In this paper we define a nil radical for fl-groups which has the property that an ideal P of an fl-group G is a semi-prime ideal if and only if G/P has no non-zero nilpotent ideals. This generalises the case...
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  51. STRONG ZERO-DIMENSIONALITY OF BIFRAMES AND BISPACES

    STRONG ZERO-DIMENSIONALITY OF BIFRAMES AND BISPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: B. Banaschewski --- Department of Mathematics and Statistics, Canada G. C.L. Brümmer --- Department of Mathematics, South Africa
    A bispace is called strongly zero-dimensional if its bispace Stone—Čech compactification is zero—dimensional. To motivate the study of such bispaces we show that among those functorial quasi—uniformities which are admissible on all completely regular bispaces, some are and others are...
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  52. RADICALS IN GENERAL Γ-NEAR-RINGS

    RADICALS IN GENERAL Γ-NEAR-RINGS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: G.L. Booth --- Department of Mathematics, South Africa
    The J 2 and J 3 radicals for zerosymmetric Γ-near-rings were recently defined by the author. In the present paper we define the J 2(0) and J 3(0) radicals for arbitrary Γ-near-rings. These radicals are sirmlar to corresponding ones which...
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  53. NILPOTENCY, SOLVABILITY AND RADICALS IN CATEGORIES

    NILPOTENCY, SOLVABILITY AND RADICALS IN CATEGORIES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: S.G. Botha --- Department of Mathematics, Applied Mathematics and Astronomy, Republic of South Africa A. Buys --- Department of Mathematics, Republic of South Africa
    Nilpotent and solvable ideals are defined and investigated in categories. The relation between the prime radical and the sum of the solvable ideals (which is also a radical) is discussed in categories. For example: If an object satisfies the maximal...
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  54. ON THE KRULL DIMENSION OF TRANSCENDENTAL EXTENSIONS OF COMMUTATIVE RINGS

    ON THE KRULL DIMENSION OF TRANSCENDENTAL EXTENSIONS OF COMMUTATIVE RINGS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: H.J. Schutte --- Department of Mathematics,
    If R is a commutative ring with identity and t 1, t 2,…, t n, are transcendental over R such that no ti is algebraic over the ring R[t 1,…, t 1-1, t i+1,…, t n] it is proved that...
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  55. ON THE SEMIPRIME IDEAL LATTICE OF A RIGHT INVARIANT RING

    ON THE SEMIPRIME IDEAL LATTICE OF A RIGHT INVARIANT RING

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: J.G. Raftery --- Department of Mathematics and Applied Mathematics, Republic of South Africa T. Sturm --- Department of Mathematics and Applied Mathematics, Republic of South Africa
    Let R be a right invariant ring and let S(R) be the lattice of all semiprime ideals of R. Let κ be an infinite cardinal. It is proved that S(R) is an algebraic lattice in which the κ-compact elements constitute...
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  56. FINITE AUTOMORPHISM GROUPS OF REDUCED COMMUTATIVE RINGS

    FINITE AUTOMORPHISM GROUPS OF REDUCED COMMUTATIVE RINGS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: H.J. Schutte --- Department of Mathematics, Republic of South Africa
    Definitions of normality and separability for unitary commutative ring extensions are given from the perspective of algebraic and transcendental ring extensions. Necessary and sufficient conditions are given for the set of subrings T i , R ⊆ T...
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  57. <em>N</em>TH ROOT ASYMPTOTICS FOR EXTREMAL ERRORS ASSOCIATED WITH SLOWLY DECREASING WEIGHTS

    NTH ROOT ASYMPTOTICS FOR EXTREMAL ERRORS ASSOCIATED WITH SLOWLY DECREASING WEIGHTS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: K.A. Driver --- Department of Mathematics, South Africa
    Let W(x) = e-Q(z) where Q(x) is even, continuous on ℝ and of slower than polynomial growth at infinity. We establish, under certain conditions on Q, nth root asymptotics for the extremal error associated with W, E np(W), 0 <...
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  58. THE INTERIORITY OF A MULTIFUNCTION

    THE INTERIORITY OF A MULTIFUNCTION

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: P. Maritz --- Department of Mathematics, South Africa
    We study the set of points of a topological space X at which a multifunction F: X → Y is interior. This paper also deals with the valuation of the Borel class of this set. The necessary examples and counterexamples...
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  59. FUZZY TOPOLOGIES OF SCOTT CONTINUOUS FUNCTIONS AND THEIR RELATION TO THE HYPERGRAPH FUNCTOR

    FUZZY TOPOLOGIES OF SCOTT CONTINUOUS FUNCTIONS AND THEIR RELATION TO THE HYPERGRAPH FUNCTOR

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Wesley Kotz&eacute; --- Department of Mathematics (Pure &amp; Applied), South Africa Tomasz Kubiak --- Instytut Matematyki, Poland
    A new definition of the hypergraph functor from the category TOP(L) of L-fuzzy topological spaces to TOP is given which avoids the strictly less-than relation on L. For L a complete lattice with enough primes it will have all the...
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  60. ON THE STRUCTURE OF MINIMAL R&lt;em&gt; &lt;sup&gt;n&lt;/sup&gt; &lt;/em&gt; ACTIONS

    ON THE STRUCTURE OF MINIMAL R n ACTIONS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: H.B. Keynes --- , USA N.G. Markley --- Department of Mathematics, USA M. Sears --- Department of Computational and Applied Mathematics, RSA
    In this paper we study several concepts and models which are relevant in describing both the topological and dynamical structure of a typical R n flow. Some of these ideas originated in our earlier papers, and those of other...
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  61. SUBDIRECT IRREDUCIBILITY AND RADICALS

    SUBDIRECT IRREDUCIBILITY AND RADICALS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Y. Fong --- Department of Mathematics, R.O.C. R. Wiegandt --- , Budapest
    We prove lemmas in Andrunakievich s-varieties on the transitivity of the relation “is an ideal of” and concerning subdirectly irreducible factor rings. Applying these lemmas we show that a Plotkin radical introduced in [8] has the ADS-property and is ideal...
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  62. SOME ASPECTS OF CONNECTEDNESS IN NEARNESS SPACES

    SOME ASPECTS OF CONNECTEDNESS IN NEARNESS SPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: D Baboolal --- Department of Mathematics and Applied Mathematics, RG Ori --- Department of Mathematics and Applied Mathematics,
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  63. ADJUNCTION OF mod &lt;em&gt;P&lt;/em&gt; EQUIVALENCES IN HOMOTOPY THEORY

    ADJUNCTION OF mod P EQUIVALENCES IN HOMOTOPY THEORY

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: P.J. Witbooi --- Department of Mathematics and Applied Mathematics, South Africa
    We formalize the adjunction of maps of localized nilpotent spaces of the homotopy type of CW-complexes. Using the semilocalization theory of M. Bendersky, in which only the higher homotopy groups are localized, we obtain an adjunction theorem with fewer nilpotency...
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  64. DIEUDONN&Eacute;&mdash;K&Ouml;THE DUALITY FOR VECTOR&mdash;VALUED FUNCTION SPACES: LOCALIZATION OF BOUNDED SETS AND BARRELLEDNESS

    DIEUDONNÉ—KÖTHE DUALITY FOR VECTOR—VALUED FUNCTION SPACES: LOCALIZATION OF BOUNDED SETS AND BARRELLEDNESS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Miguel Florencio --- , Spain Fernando Mayoral --- , Spain PedroJ. Pa&uacute;l --- , Spain
    We study Dieudonné-Köthe spaces of Lusin-measurable functions with values in a locally convex space. Let Λ be a solid locally convex lattice of scalar-valued measurable functions defined on a measure space Ω. If E is a locally convex space, define...
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  65. &alpha;-COMPACTNESS OF FUZZY TOPOLOGICAL SPACES: A CATEGORICAL APPROACH

    α-COMPACTNESS OF FUZZY TOPOLOGICAL SPACES: A CATEGORICAL APPROACH

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: I.W. Alderton --- Department of Mathematics, South Africa
    It is shown that α-compactness (due to Gantner, Steinlage and Warren) of fuzzy topological spaces is the categorical compactness (in the sense of Herrlich, Salicrup and Strecker) which arises from a factorization structure on the category of fuzzy topological spaces...
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  66. WEAK and NORM COMPACTNESS ON K&Ouml;THE-BOCHNER FUNCTION SPACES

    WEAK and NORM COMPACTNESS ON KÖTHE-BOCHNER FUNCTION SPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Santiago D&iacute;az --- Departamento de Matem&aacute;tica Aplicada II, Escuela Superior de Ingenieros Industriales, Spain Fernando Mayoral --- Departamento de Matem&aacute;tica Aplicada II, Escuela Superior de Ingenieros Industriales, Spain
    We present some characterizations of weak, weak conditional and norm compactness in spaces of vector valued order continuous Köthe function spaces. These characterizations use oscillation conditions over functions and regular methods of summability.
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  67. WEAK CONTINUITY OF MULTILINEAR MAPPINGS ON TSIRELSON&#039;S SPACE

    WEAK CONTINUITY OF MULTILINEAR MAPPINGS ON TSIRELSON'S SPACE

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Raymundo Alencar --- , Brasil Klaus Floret --- , Germany
    Continuing our investigation in [AF] about the sequential weak-to-norm continuity of multilinear mappings and polynomials between Banach spaces, some results about the Tsirelson space T, its dual T 1 and the James space (T 1) J modelled over T 1...
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  68. A GALOIS CORRESPONDENCE BETWEEN CLOSURE SPACES AND RELATIONAL SYSTEMS

    A GALOIS CORRESPONDENCE BETWEEN CLOSURE SPACES AND RELATIONAL SYSTEMS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Josef &Scaron;lapel --- Department of Mathematics, Czech Republic
    For each ordinal α < 1 we define a Galois correspondence between the category of closure spaces (i.e. sets endowed with an extensive and monotone closure operation taking value θ at θ) and the category of α-ary mono-relational systems. These...
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  69. HOMOGENEOUS FUNCTIONS DETERMINED BY CYCLIC SUBMODULES

    HOMOGENEOUS FUNCTIONS DETERMINED BY CYCLIC SUBMODULES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: C.J. Maxson --- Department of Mathematics, USA J.H. Meyer --- Department of Mathematics, Republic of South Africa
    For a unital module V over a commutative ring R, let C denote the collection of cyclic submodules. The ring ϵR(V;C) = {f ε EndR V |f(C) ⊆C, ∀C εR (V;C) has been the object of several recent studies in...
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  70. ON WEIGHTED COMPOSITION OPERATORS BETWEEN SPACES OF MEASURABLE FUNCTIONS

    ON WEIGHTED COMPOSITION OPERATORS BETWEEN SPACES OF MEASURABLE FUNCTIONS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: JuanJ. Font --- Departamento de Matem&aacute;ticas, Spain
    In this note we provide an elementary proof of the following: every automorphism S of L ∞ is of the form Sf = f o Sz for all f ε L ∞. As a first corollary we prove that if...
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  71. ON LOCALLY COUNTABLY &lt;em&gt;S&lt;/em&gt;-CLOSED AND LOCALLY RC-LINDEL&Ouml;F SPACES

    ON LOCALLY COUNTABLY S-CLOSED AND LOCALLY RC-LINDELÖF SPACES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Julian Dontchev --- Department of Mathematics, Finland Maximilian Ganster --- Department of Mathematics, Austria Chariklia Konstadilaki --- Department of Mathematics, Faculty of Sciences, Greece
    The aim of this paper is to continue the study of some topological properties weaker than S-closed, this time via a local point of view. We show that every focally countably S-closed km-perfect space is extremally disconnected as well as...
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  72. LINEAR MAPPINGS THAT PRESERVE THE DERIVATIONAL STRUCTURE OF C*-ALGEBRAS

    LINEAR MAPPINGS THAT PRESERVE THE DERIVATIONAL STRUCTURE OF C*-ALGEBRAS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: L.E. Labuschagne --- Department of Mathematics and Applied Mathematics, South Africa
    Given a C*-algebra A and a suitable set of derivations on A, we consider the algebras A n of n-differentiable elements of A as described in [B], before passing to an analysis of important classes of bounded linear maps between...
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  73. ASSOCIATIONS AND VALUATIONS

    ASSOCIATIONS AND VALUATIONS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Hans-Heinrich Brungs --- Department of Mathematics, Canada G&uuml;nter T&ouml;rner --- Fachbereich Mathematik, Germany
    Right cones are semigroups for which the lattice of right ideals is a chain and a left cancellation law holds; valuation rings, the cones of ordered groups, and initial segments of ordinal numbers are examples. Two such cones are associated...
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  74. A CONTRIBUTION OF ADAM SULIŃSKI TO RADICAL THEORY

    A CONTRIBUTION OF ADAM SULIŃSKI TO RADICAL THEORY

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Dorota Niewieczerzal --- Institute of Mathematics, Poland
    The aim of this paper is to present a contribution of Adam Suliński to radical theory.
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  75. TORSION PRERADICALS&mdash;A TOOL FOR ANALYSING RINGS

    TORSION PRERADICALS—A TOOL FOR ANALYSING RINGS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: JohnE. van den Berg --- , South Africa
    This paper surveys a selection of results in the literature on torsion preradicals; these are left exact preradical functors on the category of unital right modules over an associative ring with identity. Various well known classes of rings such as...
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  76. BANACH ALGEBRAS WITH INVOLUTION AND SPECTRAL SETS

    BANACH ALGEBRAS WITH INVOLUTION AND SPECTRAL SETS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. El Kinani --- Department of Mathematics, Morocco
    Using the notion of a spectral set introduced by von-Neumann, we give some characterizations of C+ -algebras. Two conditions, each of which is necessary and sufficient for a Banach algebra to be uniform, are also obtained.
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  77. ANALYTIC AND PROBABILISTIC THEORY OF ADDITIVE ARITHMETICAL SEMIGROUPS

    ANALYTIC AND PROBABILISTIC THEORY OF ADDITIVE ARITHMETICAL SEMIGROUPS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Wen-Bin Zhang --- Department of Mathematics, USA
    This is a short survey of the forthcoming book Number Theory Arising From Finite Fields—analytic and probabilistic theory. We give details of a number of the main theorems in the book. These are abstract prime number theorems, mean-value theorems of...
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  78. &lt;em&gt;q&lt;/em&gt;-ENGEL SERIES EXPANSIONS AND SLATER&#039;S IDENTITIES

    q-ENGEL SERIES EXPANSIONS AND SLATER'S IDENTITIES

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: GeorgeE. Andrews --- Department of Mathematics, U.S.A. Arnold Knopfmacher --- , South Africa Peter Paule --- , Austria Helmut Prodinger --- , South Africa
    Dedicated to the memory of John Knopfmacher (1937–1999)
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  79. UNIFORM SMOOTHNESS ENTAILS HAHN-BANACH

    UNIFORM SMOOTHNESS ENTAILS HAHN-BANACH

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Edmond Albius --- ERMIT, D&eacute;partement de Math&eacute;matiques et Informatique, France Marianne Morillon --- ERMIT, D&eacute;partement de Math&eacute;matiques et Informatique, France
    We show in set theory ZF (without the Axiom of Choice), that uniformly smooth normed spaces satisfy an effective and geometric form of the Hahn-Banach property. We also compare in ZF the two notions of Gâteaux differentiability and smoothness of...
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  80. THE COMPLETENESS PROBLEM IN SPACES OF PETTIS INTEGRABLE FUNCTIONS

    THE COMPLETENESS PROBLEM IN SPACES OF PETTIS INTEGRABLE FUNCTIONS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Kazimierz Musial --- , Poland
    Two subspaces of the space of Banach space valued Pettis integrable functions are considered: the space P(μ, X, var) of Pettis integrable functions with integrals of finite variation in a Banach space X and LLN(μ,X,var), the space of functions satisfying...
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  81. BROWN-McCOY RADICALS FOR GENERAL NEAR-RINGS

    BROWN-McCOY RADICALS FOR GENERAL NEAR-RINGS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: L. M&aacute;rki --- , Hungary R. Mlitz --- , Austria R. Wlegandt --- , Hungary
    Two possible ways of extending the Brown-McCoy radical to non-0-symmetric near-rings are discussed. If a Kurosh-Amitsur semisimple class So in the class No of 0-symmetric near-rings satisfies a certain condition on local units, then So is a Kurosh-Amitsur semisimple class...
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  82. GRADED MATLIS DUALITY AND APPLICATIONS TO COVERS

    GRADED MATLIS DUALITY AND APPLICATIONS TO COVERS

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: EdgarE. Enochs --- Department of Mathematics, USA J.A. L&oacute;pez-Ramos --- Department of Mathematics, USA
    We study homological properties of graded Matlis duality and apply them to get covers by Gorenstein gr-projective modules. We show that these covers are minimal graded maximal Cohen-Macaulay approximations in some cases.
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  83. New double sequence spaces of fuzzy numbers

    New double sequence spaces of fuzzy numbers

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ekrem Savaş --- Department of Mathematics, Turkey
    In this paper we introduce some new double sequence spaces of fuzzy numbers using Orlicz function and also we examine that if a sequence of fuzzy numbers is double strongly convergent with respect to an Orlicz function then it is...
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  84. The concept of quasi-uniformity in texture space and its representation

    The concept of quasi-uniformity in texture space and its representation

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Selma &Ouml;z&ccedil;ağ --- Faculty of Science, Mathematics Department, Turkey
    In this paper the author lays the foundation for a theory of quasi-di-uniformities on textures, giving descriptions in terms of direlations, dual dicovers and quasi-pseudo dimetrics. The category of quasi-di-uniformities and uniformly bicontinuous difunctions is also introduced.
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  85. Power sums of Fibonacci and Lucas numbers

    Power sums of Fibonacci and Lucas numbers

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Wenchang Chu --- , P.R. China NadiaN. Li --- , P.R China
    Polynomial representation formulae for power sums of the extended Fibonacci-Lucas numbers are established, which include, as special cases, four formulae for odd power sums of Melham type on Fibonacci and Lucas numbers, obtained recently by Ozeki and Prodinger (2009).
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  86. A particular infinite matrix and related norms

    A particular infinite matrix and related norms

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Herbert Hunziker --- , Switzerland Hans Jarchow --- , Switzerland
    We investigate norms of vectors and operators obtained from the infinite scalar matrix where thereby improving and complementing results of [5]. For any choice of and , U gives rise to a bounded linear operator which enjoys compactness properties close...
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  87. Schatten-class operators and frames

    Schatten-class operators and frames

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Yoo Young Koo --- , Republic of Korea Jae Kun Lim --- Department of Applied Mathematics, Republic of Korea
    By extending the works of Arias et al. and Balazs we present a natural sufficient condition via frames for the membership of the Schatten p-class operators for 1 ≤ p ≤ 2, and show that such a condition is not...
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  88. The Dedekind completion of &lt;em&gt;C&lt;/em&gt;(&lt;em&gt;X&lt;/em&gt;): an interval-valued functions approach

    The Dedekind completion of C(X): an interval-valued functions approach

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Nicolae Dăneţ --- , Romania
    In his paper [1] R. Anguelov described the construction of the Dedekind order completion of C(X), the set of all real-valued continuous functions defined on a completely regular topological space X, using Hausdorff continuous real interval-valued functions. The aim of...
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  89. Countably compact first countable subspaces of ordinals have the Sokolov property

    Countably compact first countable subspaces of ordinals have the Sokolov property

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: VladimirV. Tkachuk* --- Departamento de Matematicas,
    A space X is Sokolov if for any sequence {Fn : n ∈ ℕ} where Fn is a closed subset of Xn for every n ∈ ℕ, there exists a continuous map f : X → X such that nw(f(X))...
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  90. A note on almost uniform nearness frames

    A note on almost uniform nearness frames

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Themba Dube --- Department of Mathematical Sciences, South Africa MartinM. Mugochi --- Department of Mathematics, Namibia
    We show that the category of almost uniform nearness frames is co-reflective in the category of all nearness frames with interpolative uniformly below relation. This we do by actually constructing the coreflection. The resulting functor commutes with the uniform coreflection...
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  91. Automatic continuity of &lt;em&gt;n&lt;/em&gt;-homomorphisms between Fr&Eacute;chet algebras

    Automatic continuity of n-homomorphisms between FrÉchet algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: TaherG. Honary --- Faculty of Mathematical Sciences and Computer, Iran M. Najafi Tavani --- Department of Mathematics, Islamshahr Branch, Iran H. Shayanpour --- Faculty of Mathematical Sciences and Computer, Iran
    We impose a condition on a commutative regular Fréchet algebra (A, (pm )) to ensure that A/kerpm is a Fréchet Q-algebra. This implies that if θ is an n-homomorphism on certain Fréchet algebras (A, (pm )) into semisimple commutative Fréchet...
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  92. A perspective on the algebra of logic

    A perspective on the algebra of logic

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: J. G. Raftery --- School of Mathematical Sciences, South Africa
    Equations are the most basic formulas of algebra, and the logical rules for manipulating them are so intuitive that they are seldom formalized. Consequently, non-algebraic deductive systems (or ‘logics’) are very often interpreted in equational languages—although this is not always...
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  93. Self-adjoint fourth order differential operators with eigenvalue parameter dependent boundary conditions

    Self-adjoint fourth order differential operators with eigenvalue parameter dependent boundary conditions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Manfred M&ouml;ller --- The John Knopfmacher Centre for Applicable Analysis and Number Theory, South Africa Bertin Zlnsou --- The John Knopfmacher Centre for Applicable Analysis and Number Theory, South Africa
    We consider the eigenvalue problem y (4)(λ,x) − (gy′)′(λ,x) = λ 2 y(λ,x) with separated boundary conditions B j (λ)y = 0 for j = 1,…,4, where g ∈ C 1[0, a] is a real valued function, B...
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  94. Some multiple summing operators defined by the determinant of a matrix

    Some multiple summing operators defined by the determinant of a matrix

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Gabriela Badea --- Faculty of Civil Engineering, Romania
    We give some new examples of multilinear Hilbert-Schmidt and multiple summing operators, involving the determinant of a n × n-square matrix of scalars. We also determine the exact value of the Hilbert-Schmidt and multiple summing norms and we show that...
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  95. A Henstock-Kurzweil integrable vector-valued function which is not McShane integrable on any portion

    A Henstock-Kurzweil integrable vector-valued function which is not McShane integrable on any portion

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: K.M. Naralenkov --- Department of Mathematical Methods and Information Technologies, Russia
    We give an example of a function from [a, b] into c 0, which is Henstock-Kurzweil integrable on [a, b] and not McShane integrable on any nondegenerate subinterval of [a, b]. As a result, any Henstock-Kurzweil integrable function from [a,...
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  96. Compact operators which are defined by &lt;em&gt;l&lt;/em&gt; &lt;sub&gt;p&lt;/sub&gt;-spaces

    Compact operators which are defined by l p-spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Kati Ain* --- Faculty of Mathematics and Computer Science, Estonia Rauni Lillemets* --- Faculty of Mathematics and Computer Science, Estonia Eve Oja* --- Faculty of Mathematics and Computer Science, Estonia
    Let 1 ≤ p < ∞ and 1 ≤ r ≤ p*, where p* is the conjugate index of p. We say that a linear operator T from a Banach space X to a Banach space Y is (p, r)-compact...
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  97. Some determinants of Pascal-like matrices

    Some determinants of Pascal-like matrices

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Xiaoyuan Wang --- School of Science, P. R. China
    By combining the extended Cauchy double alternant with a recent theorem due to Chu (2009), we review some determinantal evaluations for Pascal-like matrices due to Krattenthaler (2002).
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  98. Normed algebras of infinitely differentiable Lipschitz functions

    Normed algebras of infinitely differentiable Lipschitz functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mortaza Abtahi --- School of Mathematics and Computer Science, Iran
    Let X be a perfect compact plane set, ω ={w n } be a weight sequence of positive numbers, and 0 < α ≤ 1. Then Lip(X, α, ω) denotes the algebra of infinitely differentiable functions f on X...
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  99. On the second conjugate of the weighted semigroup algebra for a locally compact semigroup

    On the second conjugate of the weighted semigroup algebra for a locally compact semigroup

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Saeid Maghsoudi --- Department of Mathematics, Iran Rasoul Nasr-Isfahani --- Department of Mathematical Sciences, Iran
    Let S be a topological semigroup, ω be a weight function on S, and M a (S, ω) be the weighted semigroup algebra of S. Let (S; M a (S, ω)) be the C *-algebra of all...
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  100. On the Al-Salam-Carlitz orthogonal &lt;em&gt;q&lt;/em&gt;-polynomials

    On the Al-Salam-Carlitz orthogonal q-polynomials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: L. Kh&eacute;riji --- , Tunisia
    We use the q-integral representation for the Rogers-Szegö polynomials to highlight a discrete measure of the Al-Salam-Carlitz form u(a, q) associated with the Al-SAlam-Carlitz polynomials of the first kind in the positive definite case a < 0, 0...
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  101. On harmonic starlike functions with respect to symmetric, conjugate and symmetric conjugate points

    On harmonic starlike functions with respect to symmetric, conjugate and symmetric conjugate points

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Zhi-Hong Liu --- College of Mathematics, P.R. China Yong Sun --- School of Mathematics and Econometrics, P.R. China Zhi-Gang Wang --- School of Mathematics and Statistics, P.R. China
    In the present paper, we introduce the notions of functions harmonic starlike with respect to symmetric, conjugate and symmetric conjugate points. Such results as coefficient inequalities and structural formulae for these function classes are proved.
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  102. (&lt;em&gt;ϕ, &psi;&lt;/em&gt;)-Mutations of commutative monoids with maximal endomorphism semirings

    (ϕ, ψ)-Mutations of commutative monoids with maximal endomorphism semirings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: K-T Howell --- Department of Mathematical Sciences, South Africa C.J. Maxson --- Department of Mathematics, USA
    We use commuting idempotent endomorphisms of a commutative monoid 〈S, ·, e〉 to define a new operation, ⊙, on S to obtain a medial semigroup 〈S, ⊙〉. We investigate the maximality of the semiring 〈End〈S, ⊙〉, ⊙, ◦〉 as a...
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  103. Phytoplankton responses to changes in macrophyte density in a tropical artificial pond in Zaria, Nigeria

    Phytoplankton responses to changes in macrophyte density in a tropical artificial pond in Zaria, Nigeria

    Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: AM Chia --- Department of Biological Sciences, Nigeria DN Iortsuun --- Department of Biological Sciences, Nigeria BJ Stephen --- Department of Biological Sciences, Nigeria AE Ayobamire --- Department of Biological Sciences, Nigeria Z Ladan --- , Nigeria
    The response of phytoplankton population dynamics to changes in densities of Nymphaea lotus L. and Polygonum limbatum Meisn. was studied in an artificial pond in Zaria, Nigeria, from June to November 2007. Antagonistic effects of these macrophytes on Netrium sp.,...
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  104. &ldquo;Shorthaul&rdquo; pulpwood transport in South Africa. A network analysis case study

    “Shorthaul” pulpwood transport in South Africa. A network analysis case study

    Item type: Journal Article • Journal: The Southern African Forestry Journal • Authors: Pierre A. Ackerman --- Forest Engineering, Faculty of Agricultural and Forestry Sciences, South Africa Reino E. Pulkki --- Faculty of Forestry and the Forest Environment, Canada
    Shorthaul transport, also known as secondary intermediate transport (SIT), is a feature of pulpwood transport in South Africa. SIT is an additional transport phase within traditional secondary transport. It originates at roadside landing or depot and terminates at another depot,...
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  105. Further refutation of the primary-secondary settlement hypothesis for the brown mussel &lt;em&gt;Perna perna&lt;/em&gt;

    Further refutation of the primary-secondary settlement hypothesis for the brown mussel Perna perna

    Item type: Journal Article • Journal: African Journal of Marine Science • Authors: KE Reaugh JM Harris GM Branch
    The primary-secondary settlement hypothesis, that mussels first settle in algae and then move to mussel beds, was rejected as the only mode of recruitment for the brown mussel Perna perna in a previous study at one location over one year...
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  106. The impact of season, time of defoliation and dehydration on the concentration of mimosine in &lt;em&gt;Leucaena leucocephala&lt;/em&gt; forage

    The impact of season, time of defoliation and dehydration on the concentration of mimosine in Leucaena leucocephala forage

    Item type: Journal Article • Journal: African Journal of Range &amp; Forage Science • Authors: MM Masafu MJ Linington
    This study evaluated the variation of the concentration of mimosine in Leucaena forage with season, the time of defoliation and dehydration. Fresh samples were collected randomly from Leucaena regrowth and sorted into four types of samples (primordial tips, young leaves,...
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  107. Secondary dyslipidaemia

    Secondary dyslipidaemia

    Item type: Journal Article • Journal: South African Family Practice • Authors: DJ Blom --- Division of Lipidology, Department of Medicine,
    Plasma lipid levels are determined by the interplay of environmental and genetic factors. Occasionally environmental factors may alter lipid levels significantly, resulting in secondary dyslipidaemia. The lipid phenotype in secondary dyslipidaemia is very variable (e.g. predominant hypercholesterolaemia, hypertriglyceridaemia or changes...
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  108. Secondary hypertension

    Secondary hypertension

    Item type: Journal Article • Journal: South African Family Practice • Authors: JA Ker --- Department of Internal Medicine Faculty of Health Sciences,
    Secondary hypertension is rare and the diagnosis may be challenging although, on occasion, there are clinical features indicative of a specific underlying cause. The more commonly encountered causes include renal parenchymal and vascular disease, phaeochromocytoma, endocrine causes, sleep apnoea and...
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  109. Intubation and mechanical ventilation: knowledge of medical officers at a South African secondary hospital

    Intubation and mechanical ventilation: knowledge of medical officers at a South African secondary hospital

    Item type: Journal Article • Journal: South African Family Practice • Authors: Linda van Deventer --- Department of Critical Care, South Africa
    Background: Medical officers frequently need to initiate the management of critically ill patients requiring endotracheal intubation and mechanical ventilation. The knowledge of hospital-based medical officers at a South African secondary hospital was evaluated on indications for endotracheal intubation and the...
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  110. Social comparison influences on disciplinary panels: a brief qualitative study in Kenyan secondary schools

    Social comparison influences on disciplinary panels: a brief qualitative study in Kenyan secondary schools

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Peter J.O. Aloka --- Department of Psychology &amp; Educational Foundations, Kenya Olaniyi Bojuwoye --- Department of Educational Psychology, South Africa
    This study investigated the influences of social comparisons on group polarization in decision making among members of selected Kenyan secondary school disciplinary panels. Ten participants from 10 selected secondary school disciplinary panels were involved. Semi-structured interviews were used to collect...
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  111. New formulae of BBP-type modulo 6

    New formulae of BBP-type modulo 6

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Wenlong Zhang --- School of Mathematical Sciences, P.R. China Ying Zhang --- City Institute, P.R. China
    By expressing infinite series in terms of definite integrals, we shall establish four formulae of BBP-type modulo 6 with an extra free parameter. Several new BBP-type formulae are consequently deduced.
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  112. Entire vertical graphs in Riemannian product spaces

    Entire vertical graphs in Riemannian product spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Henrique Fernandes de Lima --- Departamento de Matem&aacute;tica, Brazil
    We extend the technique developed by S.T. Yau in [21] in order to investigate the rigidity of entire vertical graphs in a Riemannian product space ℝ × Mn, whose fiber Mn is supposed to have Ricci curvature with strict sign...
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  113. Solutions of Hammerstein equations in the space &lt;em&gt;BV&lt;/em&gt; (&lt;inline-graphic xmlns:xlink=&quot;http://www.w3.org/1999/xlink&quot; id=&quot;ilg0001&quot; xlink:href=&quot;tqma_a_894675_ilg0001.gif&quot;/&gt;)

    Solutions of Hammerstein equations in the space BV ()

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: W. Aziz --- Universidad de Los Andes, Venezuela H. Leiva --- Universidad de Los Andes, Venezuela N. Merentes --- Universidad Central de Venezuela, Venezuela
    In this paper we study the existence of solutions for Hammerstein integral equations in the space of two-variables bounded variation functions BV ( )
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  114. Density by moduli and statistical convergence

    Density by moduli and statistical convergence

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Aizpuru --- Dpto. de Matem&aacute;ticas, Spain. M.C. List&aacute;n-Garc&iacute;a --- Dpto. de Matem&aacute;ticas, Spain. F. Rambla-Barreno --- Dpto. de Matem&aacute;ticas, Spain.
    By using modulus functions we introduce a new concept of density for sets of natural numbers. Consequently, we obtain a generalization of the notion of statistical convergence which is studied and characterized. As an application, we prove that the ordinary...
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  115. Goldie dimension of rings of fractions of &lt;em&gt;C&lt;/em&gt;(&lt;em&gt;X&lt;/em&gt;)

    Goldie dimension of rings of fractions of C(X)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: S. Afrooz --- Department of Mathematics, Iran F. Azarpanah --- Department of Mathematics, Iran O.A.S. Karamzadeh --- Department of Mathematics, Iran
    It is observed that X is an F-space if and only if C(X) is locally a domain (i.e., C(X)P is a domain for each prime ideal P of C(X)). Consequently, X is an F-space if and only if the primary...
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  116. On Gaussian Lipschitz spaces and the boundedness of fractional integrals and fractional derivatives on them

    On Gaussian Lipschitz spaces and the boundedness of fractional integrals and fractional derivatives on them

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Eduardo Gatto --- Department of Mathematical Sciences, USA Wilfredo O. Urbina R. --- Department of Mathematics and Actuarial Sciences, USA
    The main purpose of this paper is to study the boundedness of Gaussian fractional integrals and derivatives associated to Hermite polynomial expansions on Gaussian Lipschitz spaces Lipα (γ). To get these results we introduce formulas for these operators in terms...
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  117. Characterization of relative &lt;em&gt;n&lt;/em&gt;-isoclinism of a pair of Lie algebras

    Characterization of relative n-isoclinism of a pair of Lie algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M.R.R. Moghaddam --- Department of Mathematics, Mashhad Branch, Iran F. Saeedi --- Department of Mathematics, Mashhad Branch, Iran S. Tajnia --- Department of Mathematics, Mashhad Branch, Iran B. Veisi --- Department of Mathematics, Mashhad Branch, Iran
    In 1994, Moneyhun introduced and studied the concept of isoclinism in Lie algebras. Moghaddam and parvaneh in 2009 introduced and gave some properties of isoclinism of a pair of Lie algebras. In this paper we introduce the concept of relative...
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  118. On the inertia groups of the maximal subgroup 2&lt;sup&gt;7&lt;/sup&gt;:&lt;em&gt;Sp&lt;/em&gt;&lt;sub&gt;6&lt;/sub&gt;(2) in &lt;em&gt;Aut&lt;/em&gt;(&lt;em&gt;Fi&lt;/em&gt;&lt;sub&gt;22&lt;/sub&gt;)

    On the inertia groups of the maximal subgroup 27:Sp6(2) in Aut(Fi22)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Richard Llewellyn Fray --- Department of Mathematics and Applied Mathematics, South Africa Abraham Love Prins --- Department of Mathematics, Faculty of Military Science, South Africa
    The group 27:Sp6(2) is a maximal subgroup of Aut(Fi22) of index 694980. The group Aut(Fi22) is the full automorphism group of the smallest Fischer simple group Fi22. In this paper, we construct the character table of the inertia group 27:(25:S6)...
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  119. Convergence and completeness in asymmetrically normed sequence lattices

    Convergence and completeness in asymmetrically normed sequence lattices

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: J.J. Conradie --- Department of Mathematics and Applied Mathematics, South Africa M.D. Mabula --- Department of Mathematics and Applied Mathematics, South Africa
    If (X, ∣∣ · ∣∣) is a real normed lattice, then p(x) = ∣∣x + ∣∣ defines an asymmetric norm on X . We give suffcient conditions for (X, p) to be left-K-sequentially complete in the case where X is a...
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  120. Sequentially pure injectivity

    Sequentially pure injectivity

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: H. Barzegar --- Department of Mathematics, Iran
    Injectivity with respect to pure monomorphisms was studied before in categories of modules and categories of acts. In this paper we study this notion with respect to sequentially pure monomorphisms.
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  121. On &lt;em&gt;i&lt;/em&gt;-operators on real normed spaces

    On i-operators on real normed spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Francisco Javier Garc&iacute;a-Pacheco --- Department of Mathematics, Spain Daniele Puglisi --- Department of Mathematics, Italy Gusti van Zyl --- Department of Mathematics and Applied Mathematics, South Africa
    We gradually study i-operators on real vector spaces, on real topological vector spaces, and on real normed spaces. Among several things we prove the existence of real topological vector spaces (different from the James’ space) that are free of continuous...
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  122. Softwood sawlog secondary transport travel speed prediction for the South African forestry industry

    Softwood sawlog secondary transport travel speed prediction for the South African forestry industry

    Item type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: Pierre A Ackerman --- Department of Forest and Wood Science, South Africa Reino E Pulkki --- Department of Forest and Wood Science, South Africa Elizabeth Gleasure --- Department of Forest and Wood Science, South Africa
    The objective of this study was to develop a predictive model for travel speed of softwood sawlog timber transport (STT) vehicles over a range of forest and provincial roads of varying condition for the South African forestry industry. Data was...
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  123. A note on the effect of secondary school accounting study on university accounting performance

    A note on the effect of secondary school accounting study on university accounting performance

    Item type: Journal Article • Journal: South African Journal of Accounting Research • Authors: P van Rensburg --- Department of Accounting and Finance, G Penn --- Department of Accounting and Finance, M Haiden --- Department of Accounting and Finance,
    This study finds that taking accountancy as a matriculation subject in secondary school tends to improve a student’s final Accountancy I mark by more than can be attributed to chance. Nevertheless, prior accounting exposure explains less than 5% of the...
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  124. The effect of STC on earnings retention

    The effect of STC on earnings retention

    Item type: Journal Article • Journal: South African Journal of Accounting Research • Authors: M Graham --- Department of Accounting,
    The objective of this study is to determine whether or not the introduction of STC has resulted in South African companies retaining a greater amount of their earnings than prior to the introduction of STC. A statistical analysis of retention...
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  125. The timing of the recognition of a liability for secondary tax on companies in accordance with international financial reporting standards

    The timing of the recognition of a liability for secondary tax on companies in accordance with international financial reporting standards

    Item type: Journal Article • Journal: South African Journal of Accounting Research • Authors: E R Venter --- Department of Accounting, M Stiglingh --- Department of Taxation,
    United States Generally Accepted Accounting Practice (“US GAAP”) generally requires taxes to be measured at the rate applicable to distributed profits, while International Financial Reporting Standards (“IFRS”) requires the undistributed rate to be used. This current conflict between US GAAP...
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  126. Separating sets by upper semicontinuous quasi-continuous functions

    Separating sets by upper semicontinuous quasi-continuous functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Paulina Szczuka --- Kazimierz Wielki University, Poland
    In this paper we characterize the pairs (A0, A1) and (A−, A+) of disjoint sets which can be separated by an upper semicontinuous quasi-continuous function.
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  127. Connections between realcompactifications in various categories

    Connections between realcompactifications in various categories

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: F. Yildiz --- Hacettepe University, Turkey
    The author gives a detailed analysis of the relation between the theories of realcompactifications and compactifications in the category of ditopological texture spaces and in the categories of bitopological spaces and topological spaces.
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  128. Pseudocompact frames &lt;em&gt;L&lt;/em&gt; versus different topologies on &lt;em&gt;R&lt;/em&gt;(&lt;em&gt;L&lt;/em&gt;)

    Pseudocompact frames L versus different topologies on R(L)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sudip Kumar Acharyya --- Department of Pure Mathematics, India Goutam Bhunia --- Department of Pure Mathematics, India Partha Pratim Ghosh --- Indian Statistical Institute, North East Centre, Tezpur, India
    In this paper we have characterized pseudocompact frames L (1) via u-topology and m-topology on the rings R(L) and R* (L); (2) via some special kind of ideals of Coz L.
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  129. The formal theory of hopf algebras Part I: Hopf monoids in a monoidal category

    The formal theory of hopf algebras Part I: Hopf monoids in a monoidal category

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Hans-E. Porst --- Department of Mathematical Sciences, South Africa
    The category Hopf ℂ of Hopf monoids in a symmetric monoidal category ℂ, assumed to be locally finitely presentable as a category, is analyzed with respect to its categorical properties. Assuming that the functors “tensor squaring” and “tensor cubing” on...
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  130. The formal theory of Hopf algebras Part II: The case of Hopf algebras

    The formal theory of Hopf algebras Part II: The case of Hopf algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Hans-E. Porst --- Department of Mathematical Sciences, South Africa
    The category HopfR of Hopf algebras over a commutative unital ring R is analyzed with respect to its categorical properties. The main results are: (1) For every ring R the category HopfR is locally presentable, it is coreflective in the...
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  131. Secondary bacterial infection in active pulmonary tuberculosis

    Secondary bacterial infection in active pulmonary tuberculosis

    Item type: Journal Article • Journal: Southern African Journal of Infectious Diseases • Authors: E Shaddock --- Division of Pulmonology, Faculty of Health Sciences, Charlotte Maxeke Johannesburg Academic Hospital University of the Witwatersrand, N Bosman --- Department of Clinical Microbiology and Infectious Diseases, Charlotte Maxeke Johannesburg Academic Hospital University of the Witwatersrand, T Nana --- Department of Clinical Microbiology and Infectious Diseases, Charlotte Maxeke Johannesburg Academic Hospital University of the Witwatersrand, C Feldman --- Division of Pulmonology, Faculty of Health Sciences, Charlotte Maxeke Johannesburg Academic Hospital University of the Witwatersrand,
    Patients with pulmonary tuberculosis commonly have additional pathogens cultured in sputum, i.e. so-called potentially pathogenic bacteria. The significance of these organisms is uncertain. Previously, we demonstrated that the presence of potentially pathogenic bacteria in the sputum of a group of...
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  132. On the order of abelian surfaces of cm-type over finite prime fields

    On the order of abelian surfaces of cm-type over finite prime fields

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Annegret Weng --- Institute of Mathematics, Germany
    We consider a simple principally polarized abelian variety A of dimension g defined over a number field F with complex multiplication by an order in a CM- field K. Let ℓ be a rational prime unramified in K/ and let...
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  133. Sibling Curves of Polynomials

    Sibling Curves of Polynomials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: H. Wiggins --- Department of Mathematics and Applied Mathematics, South Africa A. Harding --- Department of Mathematics and Applied Mathematics, South Africa J. Engelbrecht --- Department of Science, Mathematics and Technology Education, South Africa W. Fouche --- Department of Quantitive Management, South Africa
    Sibling curves were demonstrated in papers [2, 3] as a novel way to visualize the zeros of complex valued functions. In this paper, we continue the work done in those papers by focusing solely on polynomials. We proceed to prove...
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  134. Ideals associated with realcompactness in pointfree function rings

    Ideals associated with realcompactness in pointfree function rings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Themba Dube --- Department of Mathematical Sciences, South Africa
    Let RL denote the ring of continuous real-valued functions on a com- pletely regular frame L. The support of an α ∈ RL is the closed quotient ↑(coz α)∗. We show that if supports are coz-quotients in L, then the set...
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  135. On Modules Which are Isomorphic to Relatively Divisible or Pure Submodules of Each Other

    On Modules Which are Isomorphic to Relatively Divisible or Pure Submodules of Each Other

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: J.E. Mac&iacute;as-D&iacute;az --- Departamento de Matem&aacute;ticas y F&iacute;sica, Mexico
    In this note, we provide a generalization of a well-known result of module theory which states that two injective modules are isomorphic when they are isomorphic to submodules of each other. More precisely, we show here that two RD-injective (respectively,...
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  136. On the class of weak almost limited operators

    On the class of weak almost limited operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Aziz Elbour --- Universit&acute;e Moulay Isma&uml;ıl, Morocco Nabil Machrafi --- Universit&acute;e Ibn Tofail, Morocco Mohammed Moussa --- Universit&acute;e Ibn Tofail, Morocco
    We introduce and study the class of weak almost limited operators. We establish a characterization of pairs of Banach lattices E, F for which every positive weak almost limited operator T : E→F is almost limited (resp. almost Dunford- Pettis)...
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  137. Essential extensions with the &lt;inline-graphic xmlns:xlink=&quot;http://www.w3.org/1999/xlink&quot; xlink:href=&quot;tqma_a_1024186_ilg0001.gif&quot;/&gt;-extending property

    Essential extensions with the -extending property

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Gary F. Birkenmeier --- Department of Mathematics, USA Adnan Tercan --- Hacettepe University, Turkey Canan C Y&uuml;cel --- Department of Mathematics, Turkey
    Let be a nonempty subset of the set of submodules of a module M . Then M is called a -extending module if for each X in there exists a direct summand D of M such that X is essential...
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  138. A closed graph theorem for order bounded operators

    A closed graph theorem for order bounded operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jan Harm van der Walt --- Department of Mathematics and Applied Mathematics, South Africa
    The closed graph theorem is one of the cornerstones of linear functional analysis in Fréchet spaces, and the extension of this result to more general topological vector spaces is a difficult problem comprising a great deal of technical difficulty. However,...
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  139. Three kinds of numerical indices of a Banach space II

    Three kinds of numerical indices of a Banach space II

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sung Guen Kim --- Department of Mathematics, Republic of Korea
    For a Banach space E and a positive integer k, we study about three kinds of numerical indices of E, the multilinear numerical index (E), the symmetric multilinear numerical index (E) and the polynomial numerical index (E). First we show...
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  140. Spaces in which every dense subset is a &lt;em&gt;G&lt;/em&gt;&lt;sub&gt;&lt;em&gt;&delta;&lt;/em&gt;&lt;/sub&gt;

    Spaces in which every dense subset is a Gδ

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M.R. Ahmadi Zand --- Mathematics Department, R. Khayyeri --- Mathematics Department,
    A topological space X is called a DGδ-space if every subset of X is a Gδ-set in its closure. In this paper we study DGδ-spaces that contains subspaces in which every dense subset is open and spaces in which every...
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  141. On character amenability of semigroup algebras

    On character amenability of semigroup algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: S.M. Maepa --- , , South Africa O.T. Mewomo --- , , South Africa
    We study the character amenability of semigroup algebras. We work on general semigroups and certain semigroups such as inverse semigroups with a finite number of idempotents, inverse semigroups with uniformly locally finite idempotent set, Brandt and Rees semigroup and study...
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  142. Measures of weak noncompactness, nonlinear leray-schauder alternatives in banach algebras satisfying condition (p) and an application

    Measures of weak noncompactness, nonlinear leray-schauder alternatives in banach algebras satisfying condition (p) and an application

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Amro Alsheikh Ali --- , , Tunisia Afif Ben Amar --- , , Tunisia
    In this paper, we establish some new nonlinear Leray-Schauder alternatives for the sum and the product of weakly sequentially continuous operators in Banach algebras satisfying certain sequential condition (P). The main condition in our results is formulated in terms of...
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  143. On Order Bounded Subsets of Locally Solid Riesz Spaces

    On Order Bounded Subsets of Locally Solid Riesz Spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Liang Hong --- , , USA
    In a topological Riesz space there are two types of bounded subsets: order bounded subsets and topologically bounded subsets. It is natural to ask (1) whether an order bounded subset is topologically bounded and (2) whether a topologically bounded subset...
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  144. Integral and discrete representations of some &lt;em&gt;H&lt;/em&gt; &lt;sub&gt; &lt;em&gt;q&lt;/em&gt; &lt;/sub&gt;-semiclassical forms

    Integral and discrete representations of some H q -semiclassical forms

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Manoubi Mejri --- , , Tunisia
    The aim of this paper is to deduce integral and discrete representations of some H q -semiclassical forms of class one. These forms were studied by B. Bouras and F. Marcellan in [1], (Quadratic decomposition of a family of...
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  145. Tightness relative to some (co)reflections in topology

    Tightness relative to some (co)reflections in topology

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Richard N. Ball --- , , U.S.A Bernhard Banaschewski --- , , Canada Tom&aacute;&scaron; Jakl --- , , N&aacute;m Ale&scaron; Pultr --- , , N&aacute;m Joanne Walters-Wayland --- , , U.S.A.
    We address what might be termed the reverse reflection problem: given a monoreflection from a category A onto a subcategory B, when is a given object B ∈ B the reflection of a proper subobject? We start with a well...
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  146. Nutritional environment at secondary schools in Bloemfontein, South Africa

    Nutritional environment at secondary schools in Bloemfontein, South Africa

    Item type: Journal Article • Journal: South African Journal of Clinical Nutrition • Authors: L Meko --- Department of Nutrition and Dietetics, Faculty of Health Sciences, M Slabber-Stretch --- Department of Nutrition and Dietetics, Faculty of Health Sciences, C Walsh --- Department of Nutrition and Dietetics, Faculty of Health Sciences, S Kruger --- School of Physiology and Nutrition, M Nel --- Department of Biostatistics, Faculty of Health Sciences,
    Objective: The objective was to determine the nutritional environment at secondary schools in Bloemfontein, Free State province.
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  147. On the Riesz representation theorem and integral operators

    On the Riesz representation theorem and integral operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mangatiana A. Robdera --- Department of Mathematics, Botswana
    We present a Riesz representation theorem in the setting of extended integration theory as introduced in [6]. The result is used to obtain boundedness theorems for integral operators in the more general setting of spaces of vector valued extended integrable...
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  148. Separating sets by Świa̧tkowski functions

    Separating sets by Świa̧tkowski functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Marcin Kowalewski --- Kazimierz Wielki University, Poland Paulina Szczuka --- Kazimierz Wielki University, Poland
    In this paper we characterize the pairs (A0, A1) and (A−, A+) of disjoint sets which can be separated by a Świa̧tkowski function.
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  149. The character table of an involution centralizer in the Dempwolff group 2&lt;sup&gt;5&middot;&lt;/sup&gt;&lt;em&gt;GL&lt;/em&gt;&lt;sub&gt;5&lt;/sub&gt;(2)

    The character table of an involution centralizer in the Dempwolff group 25·GL5(2)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Abraham Love Prins --- Department of Mathematics, Faculty of Military Science, South Africa
    The Dempwolff group D = 25· GL5(2) has an involution centralizer of the type 25· (24 :GL4(2)) of index 31 and has order 10321920. In this paper, the Fischer-Clifford matrices of the non-split extension are computed. Then the character table...
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  150. The use of glyphosate for the management of secondary coppice regrowth in a &lt;em&gt;Eucalyptus grandis&lt;/em&gt; &times; &lt;em&gt;E. urophylla&lt;/em&gt; coppice stand in Zululand, South Africa

    The use of glyphosate for the management of secondary coppice regrowth in a Eucalyptus grandis × E. urophylla coppice stand in Zululand, South Africa

    Item type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: Jonathan C Roberts --- School of Natural Resource Management, South Africa Keith M Little --- School of Natural Resource Management, South Africa Marnie E Light --- Institute for Commercial Forestry Research, South Africa
    In South Africa, commercial eucalypt stands may be regenerated through the stepwise reduction of coppice shoots following felling. The development of secondary coppice regrowth following these reduction operations results in competition with the remaining stems, possibly resulting in a reduction...
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  151. Interpolating sequences for &lt;em&gt;H&lt;sup&gt;&infin;&lt;/sup&gt;&lt;/em&gt;(&lt;em&gt;B&lt;sub&gt;H&lt;/sub&gt;&lt;/em&gt;)

    Interpolating sequences for H∞(BH)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Alejandro Miralles --- IMAC and Departament de Matem&agrave;tiques, Spain
    We prove that under the extended Carleson’s condition, a sequence (xn) ⊂ BH is linear interpolating for H∞(BH) for an infinite dimensional Hilbert space H. In particular, we construct the interpolating functions for each sequence and find a bound for...
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  152. The Zero Divisor Graph of 2 &times; 2 Matrices Over a Field

    The Zero Divisor Graph of 2 × 2 Matrices Over a Field

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ali Reza Ashrafi --- Department of Pure Mathematics, Faculty of Mathematical Sciences, I.R. Iran Adel Tadayyonfar --- Department of Pure Mathematics, Faculty of Mathematical Sciences, I.R. Iran
    A zero divisor graph, Γ(R), is formed from a ring R by having each element of Z(R) \ {0} to be a vertex in the graph and having two vertices u and v adjacent if the corresponding elements from the...
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  153. A unified view of the Dedekind completion of pointfree function rings

    A unified view of the Dedekind completion of pointfree function rings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Javier Guti&eacute;rrez Garc&iacute;a --- Department of Mathematics, Spain Imanol Mozo Carollo --- Department of Mathematics, Spain Jorge Picado --- CMUC, Department of Mathematics, Portugal
    We provide the appropriate unifying framework for the various descriptions of the Dedekind completion of the ring C(L) of continuous real functions on a frame L. It is based on suitable Galois connections and a general result about Galois connections,...
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  154. Weakly almost periodic functionals on certain Banach algebras

    Weakly almost periodic functionals on certain Banach algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Rasoul Nasr-Isfahani --- Department of Mathematical Sciences, Iran Mehdi Nemati --- Department of Mathematical Sciences, Iran
    For a Lau algebra A, we study the Banach space WAP(A) of all weakly almost periodic functionals on A to obtain some equivalent conditions for the existence of topological left invariant means on a topological left introverted subspace X of...
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  155. Domination spaces and factorization of linear and multilinear summing operators

    Domination spaces and factorization of linear and multilinear summing operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Dahmane Achour --- Universit&aacute;e Mohamed Boudiaf-M&rsquo;sila, Laboratoire d&rsquo;Analyse Fonctionnelle et G&eacute;eom&eacute;etrie des Espaces, Algeria Elhadj Dahia --- Universit&aacute;e Mohamed Boudiaf-M&rsquo;sila, Laboratoire d&rsquo;Analyse Fonctionnelle et G&eacute;eom&eacute;etrie des Espaces, Algeria Pilar Rueda --- Departamento de Ańalisis Matem&aacute;atico Universidad de Valencia, Spain Enrique A. S&aacute;nchez-P&eacute;rez --- Instituto Universitario de Matem&aacute;atica Pura y Aplicada, Universitat Polit&egrave;ecnica de Val&egrave;encia, Spain
    It is well known that not every summability property for multilinear operators leads to a factorization theorem. In this paper we undertake a detailed study of factorization schemes for summing linear and nonlinear operators. Our aim is to integrate under...
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  156. Predictors of superstitious beliefs

    Predictors of superstitious beliefs

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Patrick Kwaku Ofori --- School of Health and Allied Sciences, David Tod --- School of Sport and Exercise Sciences, UK David Lavallee --- School of Sport, UK
    This study investigated whether relationships exist among personal control, coping mechanism, primary control, secondary control and superstitious beliefs. The participants were 375 Ghanaian student athletes (females = 44%). They completed measures of self-reported superstitious beliefs, personal control, coping mechanisms, primary...
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  157. Eigenprojections and functions of a square matrix

    Eigenprojections and functions of a square matrix

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Christoph Hamburger --- University of Bonn, Germany
    We present polynomials for the eigenprojections or Frobenius covariants of a matrix A ∈ C n ×n . They allow for a computation of a function of A by a generalization of the Sylvester formula.
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  158. An infinite family of cubics with emergent reducibility at depth 1

    An infinite family of cubics with emergent reducibility at depth 1

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jason I. Preszler --- Learning Centers and Department of Mathematics and Statistics, USA
    A polynomial f (x) has emergent reducibility at depth n if f◦k (x) is irreducible for 0 ≤ k ≤ n − 1 but f◦n(x) is reducible. In this paper we prove that there are infinitely many irreducible cubics f...
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  159. The Yosida space and representation of the projectable hull of an archimedean &lt;em&gt;ℓ&lt;/em&gt;-group with weak unit

    The Yosida space and representation of the projectable hull of an archimedean ℓ-group with weak unit

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Anthony W. Hager --- Department of Mathematics and CS, USA Warren Wm. McGovern --- H.L. Wilkes Honors College, USA
    W is the category of archimedean ℓ-groups with designated weak order unit. The full subcategory of W of objects for which the unit is strong unit is denoted by W∗; such ℓ-groups are called bounded. Thus arises a coreflection ...
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  160. Approximate cohomology in Banach algebras

    Approximate cohomology in Banach algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Pourabbas --- Faculty of Mathematics and Computer Science, Iran A. Shirinkalam --- Faculty of Mathematics and Computer Science, Iran
    We introduce the notions of approximate cohomology and approximate homotopy in Banach algebras and we study the relation between them. We show that the approximate homotopically equivalent cochain complexes give the same approximate cohomologies. As a special case, approximate Hochschild...
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  161. Sibling curves of quadratic polynomials

    Sibling curves of quadratic polynomials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Harry Wiggins --- Department of Mathematics and Applied Mathematics, South Africa Ansie Harding --- Department of Mathematics and Applied Mathematics, South Africa Johann Engelbrecht --- Department of Science, Mathematics and Technology Education, South Africa
    Sibling curves were demonstrated in [1, 2] as a novel way to visualize the zeroes of real valued functions. In [3] it was shown that a polynomial of degree n has n sibling curves. This paper focuses on the algebraic...
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  162. A note on number fields having reciprocal integer generators

    A note on number fields having reciprocal integer generators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Toufik Za&iuml;mi --- Department of Mathematics and Statistics, College of Science, Saudi Arabia
    We prove that a totally complex algebraic number field K, having a conjugate which is not closed under complex conjugation, can be generated by a reciprocal integer, when the Galois group of its normal closure is contained in the hyperoctahedral...
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  163. On the Krull intersection theorem in function algebras

    On the Krull intersection theorem in function algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Raymond Mortini --- Universit&eacute; de Lorraine, France Rudolf Rupp --- Fakult&auml;t f&uuml;r Angewandte Mathematik, Physik und Allgemeinwissenschaften, Germany Amol Sasane --- Department of Mathematics, United Kingdom
    A version of the Krull intersection theorem states that for Noetherian integral domains the Krull intersection ki(I) of every proper ideal I is trivial; that is We investigate the validity of this result for various function algebras R, present ideals I...
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  164. Berezin symbols and Borel summability

    Berezin symbols and Borel summability

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M.T. Garayev --- Department of Mathematics, College of Science, Saudi Arabia M. G&uuml;rdal --- Department of Mathematics, College of Science, Turkey U. Yamancı --- Department of Mathematics, College of Science, Turkey
    We prove in terms of so-called Berezin symbols some theorems for Borel summability method for sequences and series of complex numbers. Namely, we characterize the Borel convergent sequences and series; prove regularity of Borel summability method, and prove a new...
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  165. Influence of temperature, aluminium chloride toxicity and exposure to &lt;em&gt;Bacillus subtilis&lt;/em&gt; on the germination of okra

    Influence of temperature, aluminium chloride toxicity and exposure to Bacillus subtilis on the germination of okra

    Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: Matsobane T Mathiba --- Department of Agriculture and Animal Health, South Africa Khayalethu Ntushelo --- Department of Agriculture and Animal Health, South Africa Fhatuwani Mudau --- Department of Agriculture and Animal Health, South Africa
    Influences of heat, aluminium chloride concentration and exposure to Bacillus subtilis on germination of okra seed were investigated. A factorial experiment was conducted using Petri dish assays, and seed germination percentage and coleoptile length were recorded for the different treatments...
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  166. A note on non-monogenity of number fields arised from sextic trinomials

    A note on non-monogenity of number fields arised from sextic trinomials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Anuj Jakhar --- Indian Institute of Technology (IIT), India Sumandeep Kaur --- Panjab University, India
    Let K = Q (θ) be an algebraic number field with θ a root of an irreducible polynomial f(x) = x 6 + axm + b belonging to ℤ[x] and 1 ≤ m ≤ 5. Let OK be the...
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  167. Integer partitions into Diophantine pairs

    Integer partitions into Diophantine pairs

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: F. Bencherif --- USTHB University, Algeria N. Benyahia-Tani --- Algiers 3 University, Algeria S. Bouroubi --- USTHB University, Algeria O. Kihel --- Brock University, Canada Z. Yahi --- Abderahmane Mira University, Algeria
    Let n, a and b be positive integers. The pair (a, b) is called an integer partition of n into Diophantine pair if n = a + b, ab + 1 is a perfect square and a > b. In...
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  168. On additive groups of associative and commutative rings

    On additive groups of associative and commutative rings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: R.R. Andruszkiewicz --- Institute of Mathematics, Poland M. Woronowicz --- Institute of Mathematics, Poland
    The characterization of (A)CR-groups studied by Shalom Feigelstock [‘Additive groups of commutative rings’, Quaest. Math. 23 (2000), 241–245] is complemented. In particular, the theorem characterizing mixed ACR-groups is proved and numerous new examples of (A)CR-group are given. Abelian groups A...
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  169. On weak-star &lt;em&gt;p&lt;/em&gt;-convergent operators

    On weak-star p-convergent operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jan H. Fourie --- Unit for Business Mathematics and Informatics, South Africa Elroy D. Zeekoei --- Unit for Business Mathematics and Informatics, South Africa
    The purpose of this article is to introduce and study the notion of “weak* p-convergent operator”. We discuss the relationship between the weak* p-convergent operators and the p-convergent operators, a class of operators that was introduced in the paper [4]...
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  170. On the isomorphism of injective objects in Grothendieck categories

    On the isomorphism of injective objects in Grothendieck categories

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: L.M. Gurrola-Ramos --- Centro de Ciencias B&aacute;sicas, Mexico Siegfried Mac&iacute;as --- Centro de Ciencias B&aacute;sicas, Mexico J.E. Mac&iacute;as-D&iacute;az --- Departamento de Matem&aacute;ticas y F&iacute;sica, Mexico
    Recently, some of the authors of the present note provided a generalization of Bumby’s theorem to the injectivity of modules over some classes of monomor-phisms. The question of whether Bumby’s criterion could be extended to more general classes of categories...
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  171. Separating sets by functions with a closed graph

    Separating sets by functions with a closed graph

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jolanta Kosman --- Kazimirz Wielki University, Poland
    In this paper we characterize the pairs (A−, A+) of disjoint subsets of a perfectly normal topological space which can be separated by a function with a closed graph.
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  172. On the first stability eigenvalue of hypersurfaces in the Euclidean and hyperbolic spaces

    On the first stability eigenvalue of hypersurfaces in the Euclidean and hyperbolic spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: C&iacute;cero P. Aquino --- Departamento de Matem&aacute;tica, Brazil Henrique F. de Lima --- Departamento de Matem&aacute;tica, Brazil F&aacute;bio R. dos Santos --- Departamento de Matem&aacute;tica, Brazil Marco A.L. Vel&aacute;squez --- Departamento de Matem&aacute;tica, Brazil
    In this paper, we obtain upper bounds for the first eigenvalue of the stability operator of a closed constant mean curvature hypersurface ∑n immersed either in the Euclidean space ℝn+1 or in the hyperbolic space ℍn+1, n ≥ 2, in...
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  173. Completion of a fractal structure

    Completion of a fractal structure

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: J.F. G&aacute;lvez-Rodr&iacute;guez --- Department of Mathematics, Spain M.A. S&aacute;nchez-Granero --- Department of Mathematics, Spain
    Fractal structures were introduced to characterize non-archimedean quasi-metrization, and there is a strong relationship between these two concepts. In this paper we give a construction of a completion of a fractal structure by using inverse limits of a sequence of...
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  174. The Ellis semigroup of a nonautonomous discrete dynamical system

    The Ellis semigroup of a nonautonomous discrete dynamical system

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: S. Garc&iacute;a-Ferreira --- Centro de Ciencias Matem&aacute;ticas, M&eacute;xico M. Sanchis --- Institut de Matem&aacute;tiques i Aplicacions de Castell&oacute; (IMAC), Universitat Jaume I, Spain
    We introduce the Ellis semigroup of a nonautonomous discrete dynamical system (X, f1,∞) when X is a metric compact space. The underlying set of this semigroup is the pointwise closure of in the space XX. By using the convergence of...
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  175. Summability of multilinear forms on classical sequence spaces

    Summability of multilinear forms on classical sequence spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Tony Nogueira --- Departamento de Matem&aacute;tica, Brazil Pilar Rueda --- Departamento de An&aacute;lisis Matem&aacute;tico, Valencia
    We present an extension of the Hardy-Littlewood inequality for multi-linear forms. This extension combines repetitions of indexes in the summands and perturbation of the exponent. In particular, we recover a recent result due to G. Araujo and D. Pellegrino.
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  176. Open problems in Banach spaces and measure theory

    Open problems in Banach spaces and measure theory

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jos&eacute; Rodr&iacute;guez --- Dpto. de Ingenier&iacute;a y Tecnolog&iacute;a de Computadores, Facultad de Inform&aacute;tica, Spain
    We collect several open questions in Banach spaces, mostly related to measure theoretic aspects of the theory. The problems are divided into five categories: miscellaneous problems in Banach spaces (non-separable Lp spaces, compactness in Banach spaces, w∗-null sequences in dual...
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  177. Composition operator on &Lambda;&lt;sub&gt;????&lt;/sub&gt;&lt;sup&gt;&lt;em&gt;p&lt;/em&gt;&lt;/sup&gt;(&lt;em&gt;w&lt;/em&gt;) spaces

    Composition operator on Λ????p(w) spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ren&eacute; Erlin Castillo --- Departamento de Matem&aacute;ticas, Colombia Cruz Suarez --- Departamento de Matem&aacute;ticas, Venezuela Eduard Trousselot --- Departamento de Matem&aacute;ticas, Venezuela
    In this paper we give an overview of the Λ????p(w) spaces and also characterize the boundedness and compactness of the composition operator on weighted Lorentz spaces.
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  178. Linear topologies and sequential compactness in topological modules

    Linear topologies and sequential compactness in topological modules

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Francisco Javier Garc&iacute;a-Pacheco --- Department of Mathematics, Spain Pablo Piniella --- Department of Mathematics, Spain
    We prove that an absolute semi-valued ring is first-countable if the set of invertibles is separable and its closure contains 0. We also show that every linearly topologized topological module over an absolute semi-valued ring whose invertibles approach 0 has...
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  179. On preferential Sylow fuzzy subgroups

    On preferential Sylow fuzzy subgroups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: B.B. Makamba --- Department of Mathematics, South Africa V. Murali --- Department of Mathematics (Pure &amp; Applied), South Africa
    In this paper, for a prime p, we propose some plausible definitions for the notion of Sylow fuzzy p-subgroup of a finite group. We derive a number of results for finite fuzzy groups using one of the proposed definitions. We...
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  180. Subgroups with large relative commutativity degree

    Subgroups with large relative commutativity degree

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M. Farrokhi --- Institute for Advanced Studies in Basic Sciences (IASBS), and Center for Research in Basic Sciences and Contemporary Technologies, IASBS, Iran Hesam Safa --- Department of Mathematics, Faculty of Basic Sciences, Iran
    The order of subgroups with large relative commutativity degrees are determined. Also a relationship between the number of relative commutativity degrees of a group and the length of its subgroup chains is obtained.
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  181. For eagles only: probably the most difficult proof of the Arzel&agrave;-Ascoli theorem &ndash; via the Stone-Čech compactification

    For eagles only: probably the most difficult proof of the Arzelà-Ascoli theorem – via the Stone-Čech compactification

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Marek W&oacute;jtowicz --- Instytut Matematyki, Poland
    Let C(K) denote the Banach space of all (real or complex) continuous functions on a compact Hausdorff space K.
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  182. A South African softwood sawtimber supply chain case study

    A South African softwood sawtimber supply chain case study

    Item type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: Pierre A Ackerman --- Department of Forest and Wood Science, South Africa Elizabeth A van der Merwe --- Department of Forest and Wood Science, South Africa Reino E Pulkki --- Department of Forest and Wood Science, South Africa
    Supply chain management principles were analysed by investigating the effects of smaller-scale and incremental interventions in a forest-to-mill value chain on financial returns and forest resource use in an Eastern Cape case study area. Three previous studies provided input by...
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  183. Generalized 2-local isometries of spaces of continuously differentiable functions

    Generalized 2-local isometries of spaces of continuously differentiable functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Maliheh Hosseini --- Department of Mathematics, Iran
    Let C(n) (I) denote the Banach space of n-times continuously differentiable functions on I = [0, 1], equipped with the norm ||f||n = max { |f(0)|, |fʹ(0)|, … , |f(n–1)(0)|, ||f(n)||∞} (f ) ∈ C(n) (I)), where ||·||∞ is the supremum norm...
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  184. Subordination and superordination results for analytic functions with respect to symmetrical points

    Subordination and superordination results for analytic functions with respect to symmetrical points

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: S.Z.H. Bukhari --- Department of Mathematics, Pakistan T. Bulboacă --- Faculty of Mathematics and Computer Science, Romania M.S. Shabbir --- Department of Mathematics, Pakistan
    The theory of symmetric functions has many applications in the investigation of fixed points, estimation of absolute values of some integrals and obtaining the results of the type of Cartan’s uniqueness theorem. In this paper, we solve some differential subordinations...
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  185. Lamron &lt;em&gt;ℓ&lt;/em&gt;-groups

    Lamron ℓ-groups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Papiya Bhattacharjee --- Penn State Behrend, School of Science, Warren Wm. McGovern --- H.L. Wilkes Honors College,
    The article introduces a new class of lattice-ordered groups. An ℓ-group G is lamron if Min(G)−1 is a Hausdorff topological space, where Min(G)−1 is the space of all minimal prime subgroups of G endowed with the inverse topology. It will...
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  186. A lattice-theoretic approach to arbitrary real functions on frames

    A lattice-theoretic approach to arbitrary real functions on frames

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Imanol Mozo Carollo --- Department of Mathematics, Spain
    In this paper we model discontinuous extended real functions in pointfree topology following a lattice-theoretic approach, in such a way that, if L is a subfit frame, arbitrary extended real functions on L are the elements of the Dedekind-MacNeille completion...
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  187. On some parallelism between complete regularity and zero-dimensionality

    On some parallelism between complete regularity and zero-dimensionality

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Oghenetega Ighedo --- Department of Mathematical Sciences, South Africa Martin M. Mugochi --- Department of Mathematics, Namibia
    We explore some parallelism between the categories CRFrm and 0DFrm of completely regular frames and zero-dimensional frames, respectively, with a view to establishing zero-dimensional analogues of C*-quotients. A lattice homomorphism between the cozero parts of two completely regular frames can...
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  188. Some results on (&lt;em&gt;k, &mu;&lt;/em&gt;)&prime;-almost Kenmotsu manifolds

    Some results on (k, μ)′-almost Kenmotsu manifolds

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Yaning Wang --- School of Mathematics and Information Sciences, P.R. China Wenjie Wang --- School of Mathematical Sciences, P.R. China
    In this paper, we study the Weyl conformal curvature tensor ???? and the concircular curvature tensor ???? on a (k, μ)′-almost Kenmotsu manifold M2n+1 of dimension greater than 3. We obtain that if M2n+1 satisfies either R · ???? =...
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  189. A torsion-free abelian group of finite rank exists whose quotient group modulo the square subgroup is not a nil-group

    A torsion-free abelian group of finite rank exists whose quotient group modulo the square subgroup is not a nil-group

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: R.R. Andruszkiewicz --- Institute of Mathematics, University of Białystok, Poland M. Woronowicz --- Institute of Mathematics, University of Białystok, Poland
    The first example of a finite rank torsion-free abelian group A such that the quotient group of A modulo the square subgroup of A is not a nil-group is indicated (in both cases of associative and general rings). In particular,...
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  190. A note on subsymmetric renormings of Banach spaces

    A note on subsymmetric renormings of Banach spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: J.L. Ansorena --- Department of Mathematics and Computer Sciences, Spain
    We revisit the concept of a subsymmetric norm and construct a subsymmetric renorming of a Banach space with a subsymmetric basis. As a by-product of our work we introduce the concept of a lower symmetric basis and investigate its connection...
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  191. The reciprocal of the weighted geometric mean of many positive numbers is a Stieltjes function

    The reciprocal of the weighted geometric mean of many positive numbers is a Stieltjes function

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Feng Qi --- Institute of Mathematics, Henan Polytechnic University, China Bai-Ni Guo --- School of Mathematics and Informatics, Henan Polytechnic University, China
    In the paper, by the Cauchy integral formula in the theory of complex functions, an integral representation for the reciprocal of the weighted geometric mean of many positive numbers is established. As a result, the reciprocal of the weighted geometric...
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  192. Characterizations of new Cohen summing bilinear operators

    Characterizations of new Cohen summing bilinear operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Dumitru Popa --- Department of Mathematics, Romania
    We prove two characterizations of new Cohen summing bilinear operators. The first one is: Let X, Y and Z be Banach spaces, 1 < p < ∞, V : X × Y → Z a bounded linear operator and n...
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  193. The order of starlikeness of some classes of strongly starlike functions

    The order of starlikeness of some classes of strongly starlike functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jin-Lin Liu --- Department of Mathematics, China Rekha Srivastava --- Department of Mathematics and Statistics, Canada
    In this paper we consider the order of strongly starlikeness for functions in Silverman’s class ????b and in the generalized Mocanu’s class M (α, β1, β2). Some previous results are improved.
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  194. Two point-picking games derived from a property of function spaces

    Two point-picking games derived from a property of function spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Vladimir V. Tkachuk --- Departamento de Matem&aacute;ticas,
    We present a study of two versions of the point-picking game defined by Berner and Juhasz. Given a space X there are two rivals O and P who take turns playing on X. In the n-th round Player O takes...
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  195. Robustness of the controllability for the heat equation under the influence of multiple impulses and delays

    Robustness of the controllability for the heat equation under the influence of multiple impulses and delays

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Antonio Acosta --- University Yachay Tech, School of Mathematical Sciences and Information Technology, Ecuador Hugo Leiva --- University Yachay Tech, School of Mathematical Sciences and Information Technology, Ecuador
    For many control systems in real life, impulses and delays are intrinsic properties that do not modify their behavior. Thus, we conjecture that under certain conditions the abrupt changes and delays as perturbations of a system, that could model a...
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  196. A note on weakly Lindel&ouml;f frames

    A note on weakly Lindelöf frames

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mostafa Abedi --- Esfarayen University of Technology, Iran
    The notion of σ∗-properness of a subset of a frame is introduced. Using this notion, we give necessary and sufficient conditions for a frame to be weakly Lindelöf. We show that a frame is weakly Lindelöf if and only if...
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  197. Boundedness properties in function spaces

    Boundedness properties in function spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: L&rsquo;ubica Hol&aacute; --- Mathematical Institute, Slovakia Ljubi&scaron;a D.R. Kočinac --- University of Ni&scaron;, Serbia
    Some boundedness properties of function spaces (considered as topo- logical groups) are studied.
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  198. Uniform ergodicities and perturbation bounds of Markov chains on base norm spaces

    Uniform ergodicities and perturbation bounds of Markov chains on base norm spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Nazife Erkurşun-&Ouml;zcan --- Department of Mathematics, Faculty of Science, Turkey Farrukh Mukhamedov --- Department of Mathematical Science, College of Science, UAE
    It is known that Dobrushin's ergodicity coefficient is one of the effective tools in the investigations of limiting behavior of Markov processes. Several interesting properties of the ergodicity coefficient of a positive mapping defined on base norm spaces have been...
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  199. Some notes on connectedness in nearness frames

    Some notes on connectedness in nearness frames

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: D. Baboolal --- University of KwaZulu Natal, South Africa M.M. Mugochi --- University of Namibia, Namibia
    We study the uniform connection properties of uniform local connectedness, a weaker variant of the latter, and a certain property S in the context of nearness frames. We show that the uniformly locally connected nearness frames form a reflective subcategory...
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  200. Algebraic travelling waves for the generalized Burgers-Fisher equation

    Algebraic travelling waves for the generalized Burgers-Fisher equation

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Claudia Valls --- Departamento de Matem&aacute;tica, Portugal
    Using the definition of algebraic travelling wave solution for general 2-th order differential equations given in [9], we provide the only possible algebraic travelling wave solutions for the celebrated generalized Burgers-Fisher equation.
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  201. Two-sided inequalities for the Struve and Lommel functions

    Two-sided inequalities for the Struve and Lommel functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Bayram &Ccedil;ekim --- Department of Mathematics, Faculty of Science, Turkey Ayman Shehata --- Department of Mathematics, Faculty of Science, Assiut University, Assiut 71516, Egypt; Department of Mathematics, College of Science and Arts at Unaizah, Kingdom of Saudi Arabia H.M. Srivastava --- Department of Mathematics and Statistics, University of Victoria, Victoria, British Columbia V8W 3R4, Canada; Department of Medical Research, China Medical University Hospital, Taiwan, Republic of China
    Mathematical inequalities and other results involving such widely- and extensively-studied special functions of mathematical physics and applied mathematics as (for example) the Bessel, Struve and Lommel functions as well as the associated hypergeometric functions are potentially useful in many seemingly...
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  202. Some properties of &lt;em&gt;c&lt;/em&gt;-covers of a pair of Lie algebras

    Some properties of c-covers of a pair of Lie algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Homayoon Arabyani --- Department of Mathematics, Iran Hesam Safa --- Department of Mathematics, Faculty of Basic Sciences, Iran
    In [H. Safa and H. Arabyani, On c-nilpotent multiplier and c-covers of a pair of Lie algebras, Commun. Algebra 45(10) (2017), 4429–4434], we characterized the structure of the c-nilpotent multiplier of a pair of Lie algebras in terms of its...
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  203. Characterizations of connected orthogonality graphs of projections of Rickart &lowast;-rings

    Characterizations of connected orthogonality graphs of projections of Rickart ∗-rings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Avinash A. Patil --- M.E.S. Garware College of Commerce, India B.N. Waphare --- Centre for Advanced Study in Mathematics, Department of Mathematics, India
    In this paper, we study the orthogonality graphs (see Definition 1.2) of ortholattices. We provide a graph theoretic condition for an ortholattice to be orthomodular. We prove that, the orthogonality graphs of two orthomodular lattices are isomorphic if and only...
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  204. A note on subgroup commutativity degrees of finite groups

    A note on subgroup commutativity degrees of finite groups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Marius Tărnăuceanu --- Faculty of Mathematics, Romania
    In this note we give some new results concerning the subgroup commutativity degree of a finite group G. These are obtained by considering the minimum of subgroup commutativity degrees of all sections of G.
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  205. On &lt;em&gt;&tau;&lt;/em&gt;&ndash;covers using ideals and some of its consequences

    On τ–covers using ideals and some of its consequences

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Debraj Chandra --- Department of Mathematics, India Pratulananda Das --- Department of Mathematics, India Upasana Samanta --- Department of Mathematics, India
    In this paper we primarily introduce an ideal version of τ -covers studied in [18, 19]. We establish the inter-relationships between ℐ-τ -covers and ℐ-γ, ℐ-large [3, 5] and κ-covers[2, 7]. We also make some investigations involving the splittability and...
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  206. Singular conformable sequential differential equations with distributional potentials

    Singular conformable sequential differential equations with distributional potentials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Dumitru Baleanu --- &Ccedil;ankaya University, Turkey Fahd Jarad --- &Ccedil;ankaya University, Turkey Ekin Uğurlu --- &Ccedil;ankaya University, Turkey
    In this paper we consider the singular conformable sequential equation with distributional potentials. We present Weyl’s theory in the frame of conformable derivatives. Moreover we give two theorems on limit-point case.
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  207. A variance bound for a general function of independent noncommutative random variables

    A variance bound for a general function of independent noncommutative random variables

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mohammad Sal Moslehian --- Department of Pure Mathematics, Center of Excellence in Analysis on Algebraic Structures (CEAAS), Iran Ali Talebi --- Department of Pure Mathematics, Center of Excellence in Analysis on Algebraic Structures (CEAAS), Iran
    The main purpose of this paper is to establish a noncommutative analogue of the Efron-Stein inequality, which bounds the variance of a general function of some independent random variables. Moreover, we state an operator version including random matrices, which extends...
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  208. On non-surjective coarse isometries between Banach spaces

    On non-surjective coarse isometries between Banach spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Lixin Cheng --- School of Mathematical Sciences, China Quanqing Fang --- School of Mathematical Sciences, China Sijie Luo --- School of Mathematical Sciences, China Longfa Sun --- School of Mathematical Sciences, China
    Assume that X, Y are real Banach spaces, Y has uniform convexity of type p (≥ 1), and f: X → Y is a standard coarse isometry. In this paper, we show that if
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  209. On zero-divisors of near-rings of polynomials

    On zero-divisors of near-rings of polynomials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Abdollah Alhevaz --- Faculty of Mathematical Sciences, Iran Ebrahim Hashemi --- Faculty of Mathematical Sciences, Iran Fatemeh Shokuhifar --- Faculty of Mathematical Sciences, Iran
    In this paper, we are interested to study zero-divisor properties of a 0-symmetric nearring of polynomials R0[x], when R is a commutative ring. We show that for a reduced ring R, the set of all zero-divisors of R0[x], namely Z(R0[x]),...
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  210. On Bourbaki associated prime divisors of an ideal

    On Bourbaki associated prime divisors of an ideal

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A.R. Aliabad --- Department of Mathematics, Iran M. Badie --- Department of Basic Sciences, Iran
    Suppose R is a reduced ring. The set of Bourbaki associated prime divisors of an ideal I of R is denoted by (I) and (R) is used instead of (0). Inspired by the concept of fixed-place ideal (fixed-place family), we...
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  211. A new family of Lerch-type zeta functions interpolating a certain class of higher-order Apostol-type numbers and Apostol-type polynomials

    A new family of Lerch-type zeta functions interpolating a certain class of higher-order Apostol-type numbers and Apostol-type polynomials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Irem Kucukoğlu --- Department of Software Engineering, Faculty of Engineering and Architecture, Yilmaz Simsek --- Department of Mathematics, Faculty of Science, Turkey H.M. Srivastava --- Department of Mathematics and Statistics, Canada
    The aim of this paper is to investigate some classes of higher-order Apostol-type numbers and Apostol-type polynomials. We construct Lerch-type zeta functions which interpolate these numbers and polynomials at negative integers. Moreover, by combining some well-known identities such as the...
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  212. Use of Landsat multi-temporal imagery to assess secondary growth Miombo woodlands in Luanshya, Zambia

    Use of Landsat multi-temporal imagery to assess secondary growth Miombo woodlands in Luanshya, Zambia

    Item type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: Reuben Lungu Lembani --- School of Geography, Archaeology and Environmental Studies, South Africa Jasper Knight --- School of Geography, Archaeology and Environmental Studies, South Africa Elhadi Adam --- School of Geography, Archaeology and Environmental Studies, South Africa
    Miombo woodlands are the most extensive natural forest type in subtropical Africa, supporting the livelihood of over 100 million urban and rural settlers. These forests continue to experience extensive deforestation and land degradation due to land use land cover (LULC)...
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  213. On countably uniform closed-spaces

    On countably uniform closed-spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Hayati --- Department of Mathematics, Iran M. Namdari --- Department of Mathematics, Iran M. Paimann --- Department of Mathematics, Iran
    Let X be a topological space and Cc(X) be the functionally countable subalgbera of C(X). We call X to be a countably uniform closed-space, briefly, a CU C-space, if Cc(X) is closed under uniform convergence. We investigate that countably uniform...
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  214. Piecewise polynomials with different smoothness degrees on polyhedral complexes

    Piecewise polynomials with different smoothness degrees on polyhedral complexes

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Selma Altınok --- Department of Mathematics, Turkey Neslihan &Ouml;s Sipahi --- Department of Mathematics, Turkey
    For a given d-dimensional polyhedral complex Δ and a given degree k, we consider the vector space of piecewise polynomial functions on Δ of degree at most k with a different smoothness condition on each pair of adjacent d-faces of...
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  215. Joint discrete universality for periodic zeta-functions

    Joint discrete universality for periodic zeta-functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Antanas Laurinčikas --- Institute of Mathematics, Faculty of Mathematics and Informatics, Lithuania
    In the paper, joint universality theorems for periodic zeta functions with multiplicative coefficients and periodic Hurwitz zeta-functions are proved. The main theorem of [11] is extended, and two new joint universality theorems on the approximation of a collection of analytic...
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  216. &lt;em&gt;d&lt;/em&gt;-ideals, &lt;em&gt;f d&lt;/em&gt;-ideals and prime ideals

    d-ideals, f d-ideals and prime ideals

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: S. Safaeeyan --- Department of Mathematics, Iran A. Taherifar --- Department of Mathematics, Iran
    Let R be a commutative ring. An ideal I of R is called a d-ideal (f d-ideal) provided that for each a ∈ I (finite subset F of I) and b ∈ R, Ann(a) ⊆ Ann(b) (Ann(F) ⊆ Ann(b)) implies...
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  217. Inducibility of topological trees

    Inducibility of topological trees

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Audace A.V. Dossou-Olory --- Department of Mathematical Sciences, South Africa Stephan Wagner --- Department of Mathematical Sciences, South Africa
    Trees without vertices of degree 2 are sometimes named topological trees. In this work, we bring forward the study of the inducibility of (rooted) topological trees with a given number of leaves. The inducibility of a topological tree S is...
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  218. When separability of the space of ultra-extremal functions is preserved

    When separability of the space of ultra-extremal functions is preserved

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Collins Amburo Agyingi --- Department of Mathematical Sciences, South Africa
    The ultrametrically injective hull TX of an ultrametric space (X, d) is investigated by viewing it as the space of ultra-extremal functions over X. It turns out that the ultra-extremal functions are also ultra-Kaťetov functions, satisfying two inequalities derived from...
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  219. Practical numbers in Lucas sequences

    Practical numbers in Lucas sequences

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Carlo Sanna --- Universit&agrave; degli Studi di Torino, Italy
    A practical number is a positive integer n such that all the positive integers m ≤ n can be written as a sum of distinct divisors of n. Let (un)n≥0 be the Lucas sequence satisfying u0 = 0, u1 =...
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  220. Some new results on &lt;em&gt;H&lt;/em&gt; summability of Fourier series

    Some new results on H summability of Fourier series

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Calixto P. Calder&oacute;n --- Department of Mathematics, USA A. Susana Cor&eacute; --- Department of Mathematics, USA Wilfredo O. Urbina --- Department of Mathematical and Actuarial Sciences, USA
    In this paper we shall be concerned with Hα summability, for 0 < α ≤ 2 of the Fourier series of arbitrary L1([−π, π]) functions. The methods employed here are a modification of the real variable ones introduced by J...
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  221. Some new results on functions in &lt;em&gt;C&lt;/em&gt;(&lt;em&gt;X&lt;/em&gt;) having their support on ideals of closed sets

    Some new results on functions in C(X) having their support on ideals of closed sets

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sudip Kumar Acharyya --- Department of Pure Mathematics, India Sagarmoy Bag --- Department of Pure Mathematics, India Goutam Bhunia --- Department of Pure Mathematics, India Pritam Rooj --- NIIT University, India
    For any ideal of closed sets in X, let be the family of those functions in C(X) whose support lie on . Further let contain precisely those functions f in C(X) for which for each ϵ > 0, {x ∈...
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  222. Remarks on &lt;em&gt;&omega;&lt;/em&gt;-domination of discrete subspaces

    Remarks on ω-domination of discrete subspaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Yan-Kui Song --- Institute of Mathematics, School of Mathematical Science, P.R. China Wei-Feng Xuan --- School of Statistics and Mathematics, P.R. China
    Given a space X, we will say that a class of subsets of X is dominated by a class Ɓ if for any A ∈ , there exists a B ∈ Ɓ such that A ⊂ . In particular, all...
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  223. Separating sets in bitopological spaces by &lt;em&gt;????&lt;/em&gt;-&lt;em&gt;LSC&lt;/em&gt; and ℒ-&lt;em&gt;USC&lt;/em&gt; functions

    Separating sets in bitopological spaces by ????-LSC and ℒ-USC functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Paulina Szyszkowska --- Kazimierz Wielki University, Poland
    In this paper we characterize the pairs ⟨A0, A1⟩ and ⟨A−, A+⟩ of disjoint subsets of bitopological space (X, ????, ℒ) which can be separated by the function f : X → ℝ simultaneously lower semicontinuous in the topology ????...
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  224. The quality of feedback from outpatient departments at referral hospitals to the primary care providers in the Western Cape: a descriptive survey

    The quality of feedback from outpatient departments at referral hospitals to the primary care providers in the Western Cape: a descriptive survey

    Item type: Journal Article • Journal: South African Family Practice • Authors: Robert Mash --- Division of Family Medicine and Primary Care, South Africa Herma Steyn --- Department of Health, South Africa Muideen Bello --- Division of Family Medicine and Primary Care, South Africa Klaus von Pressentin --- Division of Family Medicine and Primary Care, South Africa Liezel Rossouw --- Department of Health, South Africa Gavin Hendricks --- Division of Family Medicine and Primary Care, South Africa Germarie Fouche --- Department of Health, South Africa Dusica Stapar --- Division of Family Medicine and Primary Care, South Africa
    Background: Coordinating care for patients is a key characteristic of effective primary care. Family physicians in the Western Cape formed a research network to enable them to perform practical research on key questions from clinical practice. The initial question selected...
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  225. Eigenvalues of Sturm-Liouville problems with distribution potentials on time scales

    Eigenvalues of Sturm-Liouville problems with distribution potentials on time scales

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ji-jun Ao --- College of Sciences, China Juan Wang --- College of Sciences, China
    The eigenvalues of a class of Sturm-Liouville problems with distribution potentials and eigenparameter-dependent boundary conditions on bounded time scales are investigated. By treating with the eigenparameter-dependent boundary condition, the governing equation with distribution potential and time scales, the results of...
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  226. Admissible classes of multivalent functions associated with Liu-Owa integral operator

    Admissible classes of multivalent functions associated with Liu-Owa integral operator

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M.K. Aouf --- Department of Mathematics, Faculty of Science, Egypt T.M. Seoudy --- Department of Mathematics, Faculty of Science, Egypt
    In this paper we investigate some applications of second order differential subordination and superordination for classes of admissible functions associated with Liu-Owa integral operator. Additionally, differential sandwich-type results are obtained.
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  227. A characterization of the &lt;em&gt;n&lt;/em&gt;-ary many-sorted closure operators and a many-sorted Tarski irredundant basis theorem

    A characterization of the n-ary many-sorted closure operators and a many-sorted Tarski irredundant basis theorem

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: J. Climent Vidal --- , Spain E. Cosme Ll&oacute;pez --- , Spain
    A theorem of single-sorted algebra states that, for a closure space (A, J ) and a natural number n, the closure operator J on the set A is n-ary if and only if there exists a single-sorted signature Σ and...
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  228. Strongly primary ideals in rings with zero-divisors

    Strongly primary ideals in rings with zero-divisors

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Abdelhaq El Khalfi --- , Morocco Najib Mahdou --- , Morocco Youssef Zahir --- , Morocco
    Let A be an integral domain with quotient field K. A. Badawi and E. Houston called a strongly primary ideal I of A if whenever x, y ∈ K and xy ∈ I, we have x ∈ I or y...
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  229. The inner site-perimeter of compositions

    The inner site-perimeter of compositions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Aubrey Blecher --- The John Knopfmacher Centre for Applicable Analysis and Number Theory, School of Mathematics, South Africa Charlotte Brennan --- The John Knopfmacher Centre for Applicable Analysis and Number Theory, School of Mathematics, South Africa Arnold Knopfmacher --- The John Knopfmacher Centre for Applicable Analysis and Number Theory, School of Mathematics, South Africa
    Compositions of n are finite sequences of positive integers Such that
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  230. Nonlinear diameter preserving maps on function spaces

    Nonlinear diameter preserving maps on function spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Juan J. Font --- Departamento de Matem&aacute;ticas (IMAC), Spain Maliheh Hosseini --- Department of Mathematics, Iran
    In this paper we study nonlinear diameter preserving mappings defined between function spaces and obtain generalizations of, basically, all known results concerning diameter preservers. In particular, we give a complete description for algebras of continuously differentiable functions, (little) Lipschitz algebras...
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  231. Geometrical representation theorems for cylindric-type algebras

    Geometrical representation theorems for cylindric-type algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mohamed Khaled --- Bahcesehir University, Turkey Tarek Sayed Ahmed --- Department of Mathematics, Faculty of Science, Egypt
    In this paper, we give new proofs of the celebrated Andréka-Resek-Thompson representability results of certain axiomatized cylindric-like algebras. Such representability results provide completeness theorems for variants of first order logic, that can also be viewed as multi-modal logics. The proofs...
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  232. Shifted Cauchy numbers

    Shifted Cauchy numbers

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Takao Komatsu --- School of Mathematics and Statistics, China Claudio Pita-Ruiz --- Universidad Panamericana, M&eacute;xico
    We introduce and study shifted Cauchy numbers as different natural extension of the classical Cauchy numbers, in particular, in terms of determinantal expressions. We give several arithmetical or combinatorial properties. We also show a determinant expression of Cauchy numbers of...
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  233. Almost cosympletic statistical manifolds

    Almost cosympletic statistical manifolds

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: İrem K&uuml;peli Erken --- Department of Mathematics, Faculty of Engineering and Natural Sciences, Turkey Cengizhan Murathan --- Department of Mathematics, Art and Science Faculty, Turkey Aziz Yazla --- Department of Mathematics, Science Faculty, Turkey
    This paper is a study of almost contact statistical manifolds. Especially this study is focused on almost cosymplectic statistical manifolds. We obtained basic properties of such manifolds. A characterization theorem and a corollary for the almost cosymplectic statistical manifold with...
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  234. Generalizations of Steffensen&rsquo;s inequality by Lidstone&rsquo;s polynomial and related results

    Generalizations of Steffensen’s inequality by Lidstone’s polynomial and related results

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Josip Pečarić --- Faculty of Textile Technology, Croatia Anamarija Peru&scaron;ić Pribanić --- Faculty of Civil Engineering, Croatia Ana Vukelić --- Faculty of Food Technology and Biotechnology, Croatia
    In this paper we obtain few valuable identities by using Lidstone’s polynomial. Further, the identities were applied for constructing new generalizations of Steffensen’s inequality, namely for (2n)−convex and (2n + 1)−convex functions. In addition, using Čebyšev and Grüss type inequalities...
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  235. On weighted dirac operators and their fundamental solutions

    On weighted dirac operators and their fundamental solutions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Judith Vanegas --- Universidad T&eacute;cnica de Manab&iacute;, Ecuador Franklin Vargas --- Universidad T&eacute;cnica de Manab&iacute;, Ecuador
    In this work we define a Dirac type operator with constants weights which factorizes the Laplace operator in the classic sense. We characterize a family of operators of this type whose weights are elements of a subspace of the Clifford...
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  236. A power of a combination of meromorphic function with its shift sharing small function with its derivative

    A power of a combination of meromorphic function with its shift sharing small function with its derivative

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Arup Dam --- Department of Mathematics, India Sujoy Majumder --- Department of Mathematics, India
    In this paper, we use the idea of normal family to investigate the situation when a power of a combination of transcendental meromorphic function with its shift shares small function with it’s derivative and obtain three results which improve and...
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  237. Contractible K&ouml;the co-echelon algebras

    Contractible Köthe co-echelon algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Krzysztof Piszczek --- Faculty of Mathematics and Computer Science, Poland
    In this note we investigate contractibility properties in the class of the so-called DF-algebras. We also give a complete characterization of contractible Köthe co-echelon algebras.
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  238. On the pointwise multipliers of the space &lt;em&gt;BMOA&lt;/em&gt;

    On the pointwise multipliers of the space BMOA

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Miroljub Jevtić --- University of Belgrade, Serbia Boban Karapetrović --- University of Belgrade, Serbia
    In this note we present a new characterization of the pointwise multipliers of the space BMOA.
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  239. Investigation of the eigenvalues and root functions of the boundary value problem together with a transmission matrix

    Investigation of the eigenvalues and root functions of the boundary value problem together with a transmission matrix

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ekin Uğurlu --- &Ccedil;ankaya University, Turkey
    In this paper, we consider a singular even-order Hamiltonian system on the union of two intervals together with appropriate boundary and transmission conditions. For investigating the spectral properties of the problem we pass to the inverse operator with an explicit...
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  240. Lorentz spaces of vector measures and real interpolation of operators

    Lorentz spaces of vector measures and real interpolation of operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: R. del Campo --- , Spain A. Fern&aacute;ndez --- , Spain F. Mayoral --- , Spain F. Naranjo --- , Spain E.A. S&aacute;nchez P&eacute;rez --- , Spain
    Using the representation of the real interpolation of spaces of p-integrable functions with respect to a vector measure, we show new factorization theorems for p-th power factorable operators acting in interpolation couples of Banach function spaces. The recently introduced Lorentz...
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  241. Bourgain discretization using Lebesgue-Bochner spaces

    Bourgain discretization using Lebesgue-Bochner spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mikhail I. Ostrovskii --- , USA Beata Randrianantoanina --- , USA
    We study the Lebesgue-Bochner discretization property of Banach spaces Y , which ensures that the Bourgain discretization modulus for Y has a good lower estimate. We prove that there exist spaces that do not have the Lebesgue-Bochner discretization property, and...
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  242. Traces of Hilbert space operators and their recent history

    Traces of Hilbert space operators and their recent history

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Albrecht Pietsch --- , Germany
    This paper surveys the recent theory of traces on ideals of Hilbert space operators. The main purpose is to summarize a new approach, which was developed by the author in the last decade. We sincerely hope that our simple and...
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  243. New spaces of matrices with operator entries

    New spaces of matrices with operator entries

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Oscar Blasco --- , Spain Ismael Garc&iacute;a-Bayona --- , Spain
    In this paper, we will consider matrices with entries in the space of operators ????(H), where H is a separable Hilbert space and consider the class of matrices that can be approached in the operator norm by matrices with a...
    View item »
  244. Associated weights for spaces of &lt;em&gt;p&lt;/em&gt;-integrable entire functions

    Associated weights for spaces of p-integrable entire functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jos&eacute; Bonet --- , Spain Elisabetta M. Mangino --- , Italy
    In analogy to the notion of associated weights for weighted spaces of analytic functions with sup-norms, p-associated weights are introduced for spaces of entire p-integrable functions, 1 ≤ p < ∞. As an application, necessary conditions for the boundedness of...
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  245. Relative interior and closure of the set of inner points

    Relative interior and closure of the set of inner points

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: F.J. Garc&iacute;a-Pacheco --- , Spain
    Internal points were introduced in the literature of topological vector spaces to characterize the finest locally convex vector topology. Very recently this concept was generalized to the one of inner points in the scope of vector spaces, which, among other...
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  246. Extension and integral representation of the finite Hilbert transform in rearrangement invariant spaces

    Extension and integral representation of the finite Hilbert transform in rearrangement invariant spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Guillermo P. Curbera --- , Spain Susumu Okada --- , Australia Werner J. Ricker --- , Germany
    The finite Hilbert transform T is a classical (singular) kernel operator which is continuous in every rearrangement invariant space X over (–1, 1) having non-trivial Boyd indices. For X = Lp , 1 < p < ∞, this operator has...
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  247. Recent progress in rings and subrings of real valued measurable functions

    Recent progress in rings and subrings of real valued measurable functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Soumyadip Acharyya --- , USA Sudip Kumar Acharyya --- , India Sagarmoy Bag --- , India Joshua Sack --- , USA
    Two separated realcompact measurable spaces (X, ) and (Y, ) are shown to be isomorphic if and only if the rings (X, ) and M(Y, ) of all real valued measurable functions over these two spaces are isomorphic. It is...
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  248. Isoclinic relative extensions of pairs of Lie algebras

    Isoclinic relative extensions of pairs of Lie algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: H. Arabyani --- , Iran S. Sheikh-Mohseni --- , Iran
    In the present paper we introduce the concept of isoclinism on the relative central extensions of pairs of Lie algebras, which forms an equivalence relation and we show that each equivalence class contains a stem relative central extension. Also, we...
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  249. Graded change of ring

    Graded change of ring

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Fred Rohrer --- , Switzerland
    We investigate scalar restriction, scalar extension, and scalar coexten- sion functors for graded modules, including their interplay with coarsening functors, graded tensor products, and graded Hom functors. This leads to several character- isations of epimorphisms of graded rings.
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  250. Comparison between Szeged indices of graphs

    Comparison between Szeged indices of graphs

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Kinkar Chandra Das --- , Republic of Korea A.R. Ashrafi --- , I.R. Iran A. Ghalavand --- , I.R. Iran
    The Szeged index Sz(G) of a simple connected graph G is the sum of the terms nu (e)nv (e) over all edges e = uv of G, where nu (e) is the number of vertices of G lying closer to...
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  251. Extension of projection mappings

    Extension of projection mappings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Pierre de Jager --- , South Africa Jurie Conradie --- , South Africa
    We provide sufficient conditions for a map between projection lattices of semi-finite von Neumann algebras to be extended to a Jordan *-homomorphism. These conditions are sufficiently general for the procedures developed herein to have numerous fundamental applications in the study...
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  252. Sibling curves of cubic polynomials

    Sibling curves of cubic polynomials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Harry Wiggins --- , South Africa
    Sibling curves are a new way to represent the zeroes of any complex-valued function. Interesting results are already known for the sibling curves of quadratic polynomials. In this article a complete investigation of sibling curves of cubic polynomials is given...
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  253. Variations of classical selection principles: An overview

    Variations of classical selection principles: An overview

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ljubi&scaron;a D.R. Kočinac --- , Serbia
    The paper is an overview of selected results on weaker forms of classical selection principles of Menger, Hurewicz, Rothberger and Gerlits-Nagy obtained in the last few years. We review some very recent results on star selection principles, an important subfield...
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  254. Nilpotent lie algebras having the Schur multiplier of maximum dimension

    Nilpotent lie algebras having the Schur multiplier of maximum dimension

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Peyman Niroomand --- , Iran Afsaneh Shamsaki --- , Iran
    Let L be an n-dimensional nilpotent Lie algebra of nilpotency class c with the derived subalgebra of dimension m. Recently, Rai proved that the dimension of Schur multiplier of L is bounded by . In this paper, in virtue of...
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  255. Approximate biflatness and approximate biprojectivity of some Banach algebras

    Approximate biflatness and approximate biprojectivity of some Banach algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Sahami --- , Iran
    In this paper, we study approximate biflatness and approximate biprojectivity of some Banach algebras. In fact, we characterize approximate biflatness of triangular Banach algebras. We also show under which conditions triangular Banach algebras are not approximately biprojective. As an application,...
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  256. Extensions of semicontinuous and quasi-continuous functions from dense subspaces

    Extensions of semicontinuous and quasi-continuous functions from dense subspaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jolanta Kosman --- , Poland
    In this paper we give a sufficient condition for existence of an extension of a lower (upper) semicontinuous function f 0 defined on a given dense subset of a topological space X to a lower (upper) semicontinuous function f :...
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  257. Some applications of exponentially separable spaces

    Some applications of exponentially separable spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Vladimir V. Tkachuk --- , Mexico
    We prove that any finite product of functionally countable spaces is functionally countable if it has the Lindelöf property. In particular, any finite product of functionally countable Lindelöf Σ-spaces is functionally countable. A Lindelöf Σ- space is functionally countable if...
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  258. Separating sets by bilaterally quasi-continuous functions

    Separating sets by bilaterally quasi-continuous functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Paulina Szyszkowska --- , Poland
    In this paper we characterize the pairs (A 0, A 1) and (A−, A +) of disjoint sets which can be separated by a bilaterally quasi-continuous function. Moreover, we characterize when two arbitrary subsets of the real line can be...
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  259. On functions determined by limit sets and the quasi-Świątkowski property

    On functions determined by limit sets and the quasi-Świątkowski property

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Katarzyna Chmielewska --- , Poland Mariola Marciniak --- , Poland
    We introduce and investigate the class of functions determined by limit sets for which at each point the intersection of the sets of left-hand and right-hand limit numbers is singleton containing value of function at this point. Next we generalize...
    View item »
  260. On the fourier algebra of certain hypergroups

    On the fourier algebra of certain hypergroups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Seyed Mahmoud Manjegani --- , Iran Jafar Soltani Farsani --- , Iran
    We consider certain classes of hypergroups and address some problems regarding their Fourier algebras, including zero product preserving maps, local derivations and weak amenability. The key tool in our approach is to show that the Fourier algebra of such hypergroups...
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  261. On numbers divisible by the product of their nonzero base &lt;em&gt;b&lt;/em&gt; digits

    On numbers divisible by the product of their nonzero base b digits

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Carlo Sanna --- , Italy
    For each integer b ≥ 3 and every x ≥ 1, let b ,0(x) be the set of positive integers n ≤ x which are divisible by the product of their nonzero base b digits. We prove...
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  262. Meromorphic function sharing entire functions IM with its first derivative

    Meromorphic function sharing entire functions IM with its first derivative

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sujoy Majumder --- , India Jeet Sarkar --- , India
    In this paper, we use the idea of normal family to investigate the problem of meromorphic function having finitely many poles that share entire functions IM with its first derivative.
    View item »
  263. Joint discrete universality for periodic zeta-functions. II

    Joint discrete universality for periodic zeta-functions. II

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Antanas Laurinčikas --- , Lithuania
    In the paper, for certain classes of operators F in the space of analytic functions, we prove the discrete universality for compositions F (ζ(s, α ; ????, ???? )), where ζ(s, α ; ???? ; ???? )...
    View item »
  264. Some expansions of functions based upon two sequences of hypergeometric polynomials

    Some expansions of functions based upon two sequences of hypergeometric polynomials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mohammad Masjed-Jamei --- , Iran H.M. Srivastava --- , Canada
    In this paper, we introduce two series expansions whose basis functions are two sequences of hypergeometric polynomials. We then present a systematic and detailed study of the general properties of each of these series expansions. We consider several illustrative examples...
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  265. Ricci &lt;em&gt;&eta;&lt;/em&gt;-parallel trans-Sasakian 3-manifolds

    Ricci η-parallel trans-Sasakian 3-manifolds

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Yan Zhao --- , P. R. China
    In this paper, we present a new characterization for a trans-Sasakian 3-manifold to be proper. More precisely, we prove that if a compact trans-Sasakian 3-manifold has η-parallel Ricci operator, then the manifold is homothetic to a cosymplectic or a Sasakian...
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  266. About porosity of some Świątkowski functions in the space of quasi-continuous functions

    About porosity of some Świątkowski functions in the space of quasi-continuous functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Gertruda Ivanova --- , Poland Aleksandra Karasńska --- , Poland
    In the paper by M. Filipczak, G. Ivanova and J. Wódka, Comparison of some families of real functions in porosity terms, Math. Slovaca 67(5) (2017), 1155–1164, it was proved that the family of quasi-continuous Świątkowski functions is porous but not...
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  267. A note on certain subrings of ℛ (&lt;em&gt;L&lt;/em&gt;)

    A note on certain subrings of ℛ (L)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Goutam Bhunia --- , India
    We introduce a new subring (L) of (L) for a completely regular frame L and characterize pseudocompact frames via these subrings. Also we obtain several sufficient conditions on L which guarantee that the cozero part of generates L. Further, we...
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  268. Dense and &sigma;-porous subsets in some families of cliquish functions

    Dense and σ-porous subsets in some families of cliquish functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Gertruda Ivanova --- , Poland Elżbieta Wagner-Bojakowska --- , Poland
    A function f: ℝ → ℝ is internally cliquish (internally quasi-continuous) if it is cliquish (quasi-continuous) and the set of discontinuity points of f is nowhere dense. We prove that the set of internally cliquish (internally quasi-continuous) functions is dense...
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  269. On some probabilistic aspects of (generalized) dicyclic groups

    On some probabilistic aspects of (generalized) dicyclic groups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mihai-Silviu Lazorec --- , Romania Marius Tărnăuceanu --- , Romania
    In this paper we study probabilistic aspects, such as the subgroup commutativity degree and the cyclic subgroup commutativity degree, of (generalized) dicyclic groups. We find explicit formulas for these quantities and we provide another example of a class of groups...
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  270. On the three questions of Bertram on locally maximal sum-free sets

    On the three questions of Bertram on locally maximal sum-free sets

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Chimere S. Anabanti --- , Nigeria
    We recently answered the three questions of Bertram in the finite abelian case in https://link.springer.com/article/10.1007/s00200-018-0364-0, Applicable Algebra in Engineering, Communication and Computing 30(2) (2019), 127–134. In this paper, we answer the nonabelian analogues of the three questions of Bertram on...
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  271. Spectra of composition operators on Fock-type spaces

    Spectra of composition operators on Fock-type spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Tesfa Mengestie --- , Norway Werkaferahu Seyoum --- ,
    This work is a continuation of our recent investigation in [15] where we characterized various topological and dynamical properties of the composition operator Cψ acting between Fock-type spaces and when both exponents p and q are finite. Now we investigate...
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  272. On the continuous dependence of solutions to a bipolynomial fractional Dirichlet-Laplace problem

    On the continuous dependence of solutions to a bipolynomial fractional Dirichlet-Laplace problem

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Marek Majewski --- , Poland
    In the paper, we consider a bipolynomial fractional Dirichlet-Laplace problem with a functional parameter u. The main goal is to prove theorems on the existence and continuous dependence of solution on functional parameter u for the above problem. Since the...
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  273. Remarks on normal distributive nearlattices

    Remarks on normal distributive nearlattices

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ismael Calomino --- , Argentina Luciano J. Gonz&aacute;lez --- , Argentina
    In this paper, we present the notions of α-ideal and α-congruence on a distributive nearlattice. We prove that the α-ideals and α-congruences of a normal distributive lattice A are in a one-to-one correspondence with the ideals and congruences of the...
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  274. Unit groups of group algebras of groups of order 20

    Unit groups of group algebras of groups of order 20

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sheere Farhat Ansari --- , India Meena Sahai --- , India
    Let F be a finite field of characteristic p. There are five non-isomorphic groups of order 20. The structure of U (FD 20) is given in [2, 6, 10] and that of U (FQ 20) is given in [3, 6],...
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  275. Settlement of the invasive mussel &lt;em&gt;Mytilus galloprovincialis&lt;/em&gt; in a warm temperate estuarine embayment in South Africa

    Settlement of the invasive mussel Mytilus galloprovincialis in a warm temperate estuarine embayment in South Africa

    Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: J Radloff --- , South Africa AN Hodgson --- , South Africa L Claassens --- , South Africa
    Mytilus galloprovincialis, a globally successful marine alien invasive species, occupies all artificial hard substrata in the embayment of the Knysna estuary, South Africa. The current study compared temporal and spatial settlement patterns of M. galloprovincialis within this environment. Settlement was...
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  276. Riemann soliton within the framework of contact geometry

    Riemann soliton within the framework of contact geometry

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M.N. Devaraja --- , India H. Aruna Kumara --- , India V. Venkatesha --- , India
    In this paper, we study contact metric manifold whose metric is a Riemann soliton. First, we consider Riemann soliton (g, V ) with V as contact vector field on a Sasakian manifold (M, g) and in this case we prove...
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  277. On some new Gaussian hypergeometric summation formulae with applications

    On some new Gaussian hypergeometric summation formulae with applications

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Insuk Kim --- , Republic of Korea T.K. Pog&aacute;ny --- , Hungary Arjun K. Rathie --- , India
    The aim of this note is to provide some new Gaussian hypergeometric summation formulae. These are further used to obtain certain new expressions for the product of hypergeometric series. Already obtained results by Bailey, Choi and Rathie and Qureshi et...
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  278. Indirect exposure to trauma: Does resilience explain the link between optimism and secondary traumatic stress among in-patient carers?

    Indirect exposure to trauma: Does resilience explain the link between optimism and secondary traumatic stress among in-patient carers?

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Rosemary C. Muomah --- , Nigeria Appollos C. Ndukuba --- , Nigeria Paul C. Odinka --- , Nigeria Kennedy U. Amadi --- , Nigeria Callista U. Nduanya --- , Nigeria Jaclyn I. Odinka --- , Nigeria Theclar C. Iyidobi --- , Nigeria
    This study examined the relationship between optimism and secondary traumatic stress (STS), including the mediating role of resilience on the association. Family carers (n = 194; female = 64.95%; married = 50%; age range = 15 to 70, mean age...
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  279. On closures of discrete sets

    On closures of discrete sets

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Santi Spadaro --- , Italy
    The depth of a topological space X (g(X)) is defined as the supremum of the cardinalities of closures of discrete subsets of X. Solving a problem of Martínez-Ruiz, Ramírez-Páramo and Romero-Morales, we prove that the cardinal inequality |X| ≤ g(X)...
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  280. Global existence and blow-up for a space and time nonlocal reaction-diffusion equation

    Global existence and blow-up for a space and time nonlocal reaction-diffusion equation

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ahmed Alsaedi --- , Saudi Arabia Mokhtar Kirane --- , France Berikbol T. Torebek --- , Kazakhstan
    A time-space fractional reaction-diffusion equation in a bounded domain is considered. Under some conditions on the initial data, we show that solutions may experience blow-up in a finite time. However, for realistic initial conditions, solutions are global in time. Moreover,...
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  281. Einstein type tensors in the generalized Riemannian space

    Einstein type tensors in the generalized Riemannian space

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Vladislava M. Stanković --- , Serbia
    In [22], V.M. Stankovíc introduced generalized Einstein type tensors of the kind θ (θ = 1, 2) in the generalized Riemannian space, and some relations which they satisfy are obtained using the first and the second kind of covariant derivative...
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  282. Topo-edaphic environment and forest plantation disturbance explain patterns of grassland species richness, composition and structure in an agro-ecological landscape, Maputaland, South Africa

    Topo-edaphic environment and forest plantation disturbance explain patterns of grassland species richness, composition and structure in an agro-ecological landscape, Maputaland, South Africa

    Item type: Journal Article • Journal: African Journal of Range &amp; Forage Science • Authors: AP Starke --- , South Africa TG O&rsquo;Connor --- , South Africa CS Everson --- , South Africa
    Grasslands of the Maputaland coastal plain are biologically diverse and provide a variety of ecosystems services. Yet grasslands in this region are vulnerable to continuing development by plantation forestry that provides economic benefits to local communities. In order to provide...
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  283. Topo-edaphic environment and forestry plantation disturbance affect the distribution of grassland forage and non-forage resources, Maputaland, South Africa

    Topo-edaphic environment and forestry plantation disturbance affect the distribution of grassland forage and non-forage resources, Maputaland, South Africa

    Item type: Journal Article • Journal: African Journal of Range &amp; Forage Science • Authors: AP Starke --- , South Africa TG O&rsquo;Connor --- , South Africa CS Everson --- , South Africa
    Grasslands are integral to rural livelihoods in southern Africa, because they provide hydrological regulation services and a variety of plant resources, including livestock fodder, medicines, and food products. To ensure ongoing provision of these resources in rapidly developing rural landscapes,...
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  284. Centralizers and isomorphism preservation of minimal factors of nearring modules

    Centralizers and isomorphism preservation of minimal factors of nearring modules

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Gary L. Peterson --- , USA Stuart D. Scott --- , New Zealand
    If N 1 is a nearring, V is a faithful tame N 1-module and N 2 is a nearring containing N 1 such that V is a faithful tame N 2-module and the N 1- and N 2-ideals of V...
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  285. Filled groups of order &lt;em&gt;pqr&lt;/em&gt; for primes &lt;em&gt;p&lt;/em&gt;; &lt;em&gt;q&lt;/em&gt; and &lt;em&gt;r&lt;/em&gt;

    Filled groups of order pqr for primes p; q and r

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Chimere S. Anabanti --- , Austria
    We classify the filled groups of order pqr for primes p, q and r. Our result confirms a conjecture of Anabanti, Erskine and Hart for these examples of soluble groups.
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  286. Finitely continuous Darboux functions

    Finitely continuous Darboux functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Marcin Kowalewski --- , Poland Mariola Marciniak --- , Poland
    In this paper we consider properties of the class of finitely continuous Darboux functions. In particular, we study some properties of the set of discontinuity points of the function from this class. We show some relations between the family of...
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  287. Practical central binomial coefficients

    Practical central binomial coefficients

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Carlo Sanna --- , Italy
    A practical number is a positive integer n such that all positive integers less than n can be written as a sum of distinct divisors of n. Leonetti and Sanna proved that, as x → +∞, the central binomial coefficient...
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  288. Weak compactness of almost L-weakly and almost M-weakly compact operators

    Weak compactness of almost L-weakly and almost M-weakly compact operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Farid Afkir --- , Morocco Khalid Bouras --- , Morocco Aziz Elbour --- , Morocco Safae El Filali --- , Morocco
    In this paper, we investigate conditions on a pair of Banach lattices E and F that tells us when every positive almost L-weakly compact (resp. almost M- weakly compact) operator T : E → F is weakly compact. Also, we...
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  289. Addendum to: &ldquo;Variations of classical selection principles: An overview&rdquo;

    Addendum to: “Variations of classical selection principles: An overview”

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ljubi&scaron;a D.R. Kočinac --- , Serbia
    In this addendum we give a few remarks about Subsection 6.2 of the paper “Variations of classical selection principles: An overview,” Quaestiones Mathematicae, https://doi.org/10.2989/16073606.2019.1601646.
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  290. A note on Tingley&rsquo;s problem and Wigner&rsquo;s theorem in the unit sphere of &lt;inline-graphic xlink:href=&quot;tqma_a_1783010_ilg0001.gif&quot;/&gt; &lt;sup&gt;&infin;&lt;/sup&gt;(&Gamma;)-type spaces

    A note on Tingley’s problem and Wigner’s theorem in the unit sphere of ∞(Γ)-type spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Dongni Tan --- , China Xiaolei Xiong --- , China
    Suppose that f : SX → SY is a surjective map between the unit spheres of two real ∞ (Γ)-type spaces X and Y satisfying the following equation
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  291. On best proximity points of interpolative proximal contractions

    On best proximity points of interpolative proximal contractions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ishak Altun --- , Vietnam Ayşenur Taşdemir --- , Turkey
    In this paper, we introduce some kinds of interpolative proximal contractions named as Reich-Rus-Ćirić and Kannan types. Then taking into account the aforementioned mappings, we give a few best proximity point results. As special cases we obtain some fixed point...
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  292. Using digital photography to study moult extent in breeding seabirds

    Using digital photography to study moult extent in breeding seabirds

    Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology • Authors: Alexis Osborne --- , South Africa Peter G Ryan --- , South Africa
    Scoring moult from live birds in the hand takes time, thereby increasing the handling stress to the birds. We show that digital photography can be used to efficiently study moult extent across multiple feather tracts. We photographed the upper wings...
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  293. On the lower Lie nilpotency index of a group algebra

    On the lower Lie nilpotency index of a group algebra

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Meena Sahai --- , India Bhagwat Sharan --- , India
    In this article, we show that if KG is a Lie nilpotent group algebra of a group G over a field K of characteristic p > 0, then tL (KG) = k if and only if tL (KG) = k,...
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  294. Approximate properties of the &lt;em&gt;p&lt;/em&gt;-Bieberbach polynomials in regions with simultaneously exterior and interior zero angles

    Approximate properties of the p-Bieberbach polynomials in regions with simultaneously exterior and interior zero angles

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: F.G. Abdullayev --- , Turkey M. Imashkyzy --- , Kyrgyz Republic P. &Ouml;zkartepe --- , Turkey
    In this paper, we study the uniform convergence of p-Bieberbach polynomials in regions with a finite number of both interior and exterior zero angles at the boundary.
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  295. Almost quasi-Yamabe solitons and gradient almost quasi-Yamabe solitons in paracontact geometry

    Almost quasi-Yamabe solitons and gradient almost quasi-Yamabe solitons in paracontact geometry

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Krishnendu De --- , India Uday Chand De --- , India
    The purpose of the present paper is to investigate the almost quasi-Yamabe soliton and gradient almost quasi-Yamabe solitons under the framework of three-dimensional normal almost paracontact metric manifolds.
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  296. Multivalued generalized graphic &lt;em&gt;&theta;&lt;/em&gt;-contraction on directed graphs and application to mixed Volterra-Fredholm integral inclusion equations

    Multivalued generalized graphic θ-contraction on directed graphs and application to mixed Volterra-Fredholm integral inclusion equations

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Lakshmi Kanta Dey --- , India Hiranmoy Garai --- , India Hemant Kumar Nashine --- , India Can Huu Nguyen --- , Vietnam
    The purpose of the present work is to introduce a generalized graphic θ-contraction conditions on a family of mappings defined on subsets of a metric space endowed with a set-transitive directed graph, and discuss common fixed point results without considering...
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  297. Joint discrete universality for periodic zeta-functions. III

    Joint discrete universality for periodic zeta-functions. III

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Antanas Laurinčikas --- , Lithuania
    In the paper, a joint theorem on the approximation of collections of analytic functions by generalized discrete shifts of zeta-functions with periodic coefficients is obtained. The latter result extend theorems of [9].
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  298. On irreducible denumerable continuous parameter circuit chains: Analysis of a generalized sample path case

    On irreducible denumerable continuous parameter circuit chains: Analysis of a generalized sample path case

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Chrysoula V. Ganatsiou --- , Greece
    By using the cycle-circuit representation theory of Markov processes we investigate the continuous parameter analogue of the existence and construction of a class of irreducible, denumerable Markov chains generated by a collection of overlapping directed weighted circuits regarding a generalized...
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  299. On the bounded sets in &lt;em&gt;C&lt;sub&gt;c&lt;/sub&gt; &lt;/em&gt;(&lt;em&gt;X&lt;/em&gt;)

    On the bounded sets in Cc (X)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Lahbib Oubbi --- , Morocco
    If X is Hausdorff topological space and Cc (X) is the topological algebra obtained by endowing the algebra C(X) of all continuous functions on X with the topology τc of uniform convergence on the compact subsets of X, then the set...
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  300. Hardy-Littlewood maximal operator on variable Lebesgue spaces with respect to a probability measure

    Hardy-Littlewood maximal operator on variable Lebesgue spaces with respect to a probability measure

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jorge Moreno --- , Venezuela Ebner Pineda --- , Ecuador Luz Rodriguez --- , Ecuador Wilfredo O. Urbina --- , USA
    In this paper we are going to prove that the Hardy-Litllewood maximal operators on variable Lebesgue spaces L p(·)(µ) with respect to a probability Borel measure µ, are weak type and strong type for two conditions of regularity on the...
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  301. Certain observations on selection principles from (a) Bornological viewpoint

    Certain observations on selection principles from (a) Bornological viewpoint

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Debraj Chandra --- , India Pratulananda Das --- , India Subhankar Das --- , India
    This article is a continuation of the study of bornological open covers and related selection principles in metric spaces done in (Chandra et al. 2020 [6]) using the idea of strong uniform convergence (Beer and Levi, 2009 [3]) on a...
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  302. The Hopf algebroid structure of differentially recursive sequences

    The Hopf algebroid structure of differentially recursive sequences

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Laiachi El Kaoutit --- , Spain Paolo Saracco --- , Belgium
    A differentially recursive sequence over a differential field is a sequence of elements satisfying a homogeneous differential equation with non-constant coefficients (namely, Taylor expansions of elements of the field) in the differential algebra of Hurwitz series. The main aim of...
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  303. On the class of U-Dunford-Pettis operators

    On the class of U-Dunford-Pettis operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Othman Aboutafail --- , Morocco Kamal El Fahri --- , Morocco Jawad H&rsquo;Michane --- , Morocco Larbi Zraoula --- , Morocco
    We introduce a new class of operators “DPu (E, Y)” which lives between the class of Dunford-Pettis, the class of AM-compact operators and that of order weakly compact “Lowc (E, Y)”, more precisely we have “DP (E, Y) ⊂ DPu...
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  304. A remark on non-surjective composition operators

    A remark on non-surjective composition operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Yunbai Dong --- , China Bentuo Zheng --- , USA
    Assume that A, B are uniform algebras on compact Hausdorff spaces X and Y, respectively, and ∂A, ∂B are the Šilov boundaries of A, B. Let T : A −1 → B− 1 be a map with T1 =...
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  305. Designs and codes from involutions of &lt;em&gt;A&lt;sub&gt;n&lt;/sub&gt; &lt;/em&gt;

    Designs and codes from involutions of An

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: J. Moori --- , South Africa
    We previously have developed two methods for constructing codes and designs from finite simple groups. In a recent paper we introduced a new method (Method 3) for constructing codes and designs from fixed points of elements of finite transitive groups...
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  306. An upper bound for the index of the center in capable groups with finite cyclic derived subgroups

    An upper bound for the index of the center in capable groups with finite cyclic derived subgroups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Marzieh Chakaneh --- , Iran Farangis Johari --- , Iran Saeed Kayvanfar --- , Iran Azam Kaheni --- , Iran
    A group G is said to be capable if it occurs as the central factor group H/Z(H) for some group H. Motivated by the results of Isaacs [11], in Proc. Amer. Math. Soc. 129(10) (2001), pp. 2853-2859, we show that...
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  307. Differential subordination related with exponential functions

    Differential subordination related with exponential functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Saima Mushtaq --- , Pakistan Mohsan Raza --- , Pakistan Janusz Sok&oacute;ł --- , Poland
    In this article, we study some first-order differential subordinations. We determine the conditions on β such that and implies . Similarly, some results are also obtained for the expressions and . We also give applications of these results to obtain...
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  308. A note on a further extension of Gauss&rsquo;s second summation theorem with an application to the extension of two well-known combinatorial identities

    A note on a further extension of Gauss’s second summation theorem with an application to the extension of two well-known combinatorial identities

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Insuk Kim --- , Korea Gradimir V. Milovanović --- , Serbia Richard B. Paris --- , UK Arjun K. Rathie --- , India
    Recently, Masjed-Jamei and Koepf established the extension of several classical summation theorems (including Gauss’s second summation theorem). Our aim in this paper is to establish a further extension of Gauss’s second summation formulas due to Masjed-Jamei and Koepf in the...
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  309. Biholomorphically projective mappings of generalized Riemannian space in the Eisenhart sense

    Biholomorphically projective mappings of generalized Riemannian space in the Eisenhart sense

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Vladislava M. Milenković --- , Serbia Milan Lj. Zlatanović --- , Serbia
    In this paper, biholomorphically projective and equitorsion biholomorphically projective mappings are defined. Some relations between corresponding curvature tensors of the generalized Riemannian spaces GRN and are obtained. At the end, invariant geometric object of equitorsion biholomorphically projective mapping are found.
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  310. First-order invariants of differential 2-forms

    First-order invariants of differential 2-forms

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: J. Mu&ntilde;oz Masqu&eacute; --- , Spain L.M. Pozo Coronado --- , Spain
    Let M be a smooth manifold of dimension 2n, and let OM be the dense open subbundle in ∧2 T*M of 2-covectors of maximal rank. The algebra of Diff M -invariant smooth functions of first order on OM is proved...
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  311. Quasi &lt;em&gt;SV&lt;/em&gt;-frames and their properties

    Quasi SV-frames and their properties

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mostafa Abedi --- , Iran
    Let P be a prime ideal of the ring of continuous real-valued functions on a completely regular frame L, i.e., L. We study many new results about the residue class domains L/P with an emphasis on determining when...
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  312. Nordhaus-Gaddum inequalities for the number of connected induced subgraphs in graphs

    Nordhaus-Gaddum inequalities for the number of connected induced subgraphs in graphs

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Eric O.D. Andriantiana --- , South Africa Audace A.V. Dossou-Olory --- , South Africa
    Let η(G) be the number of connected induced subgraphs in a graph G, and Ḡ the complement of G. We prove that η(G) + η(Ḡ) is minimum, among all n-vertex graphs, if and only if G has no induced path...
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  313. On the exponents in the factorizations of &lt;em&gt;r&lt;/em&gt; consecutive numbers

    On the exponents in the factorizations of r consecutive numbers

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Carlo Sanna --- , Italy
    Let f (n) be the number of distinct exponents in the prime factorization of the natural number n. For every r-tuple of positive integers k = (k 1, . . . , k r ) and for all...
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  314. Positive filters and links in an &lt;em&gt;ℓ&lt;/em&gt;-group

    Positive filters and links in an ℓ-group

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M. Pourgholamhossein --- , Iran M.A. Ranjbar --- , Iran
    In this paper we continue our research about links and link topologies on ℓ-groups and Riesz spaces. We show that in a Riesz space E, a link topology τ is a vector topology, if and only if the link consists...
    View item »
  315. Groups whose same-order types are arithmetic progressions

    Groups whose same-order types are arithmetic progressions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mihai-Silviu Lazorec --- , Romania Marius Tărnăuceanu --- , Romania
    The same-order type τe (G) of a finite group G is a set formed of the sizes of the equivalence classes containing the same order elements of G. In this paper, we study an arithmetical property of this set. More...
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  316. On generalized weighted composition operators acting between Fock-type spaces

    On generalized weighted composition operators acting between Fock-type spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mafuz Worku --- , Ethiopia
    In this paper, we study essential norm and Schatten class membership of the generalized weighted composition operators acting on Fock-type spaces. An asymptotic estimate for the essential norm and norm of the operators have been also provided. Moreover, we characterize...
    View item »
  317. 2-local real-linear isometries on &lt;em&gt;C&lt;/em&gt; &lt;sup&gt;(1)&lt;/sup&gt;([0, 1])

    2-local real-linear isometries on C (1)([0, 1])

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Hironao Koshimizu --- , Japan Takeshi Miura --- , Japan
    Let C (1)([0, 1]) be the Banach space of continuously differentiable functions on the closed unit interval [0, 1] equipped with the norm ||f||σ= | f (0)| +|| f ′||∞, where ||g||∞= sup{|g(t)| : t ∈ [0, 1]} for g...
    View item »
  318. A note on the density of &lt;em&gt;k&lt;/em&gt;-free polynomial sets, Haar measure and global fields

    A note on the density of k-free polynomial sets, Haar measure and global fields

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Luca Demangos --- , China Ignazio Longhi --- , India
    In this work we investigate the general relation between the density of a subset of the ring of integers D of a general global field and the Haar measure of its closure in the profinite completion . We then study...
    View item »
  319. Trans-Sasakian 3-manifolds with Einstein-like Ricci operators

    Trans-Sasakian 3-manifolds with Einstein-like Ricci operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Wenjie Wang --- , P.R. China
    Let M be a trans-Sasakian 3-manifold such that the Ricci curvature of the structure vector field vanishes. In this paper, it is proved that if M is compact, then it is homothetic to a cosymplectic manifold. Without the compactness assumption,...
    View item »
  320. The geometry of the moduli space of non-cyclic biquadratic field extensions

    The geometry of the moduli space of non-cyclic biquadratic field extensions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mpendulo Cele --- Stellenbosch University, South Africa Sophie Marques --- Stellenbosch University, South Africa
    In this paper, we investigate the existence of an elementary abelian closure in characteristic not 2 for biquadratic extensions. We discover that it exists for any non-cyclic extension. We make use of it to obtain a classification for this class...
    View item »
  321. Some notes on the paper &ldquo;On best proximity points of interpolative proximal contractions&rdquo;

    Some notes on the paper “On best proximity points of interpolative proximal contractions”

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M. Gabeleh --- Ayatollah Boroujerdi University, Iran J. Markin --- , USA
    In a recent paper [I. Altun and A. Tasdemir, On best proximity points of interpolative proximal contractions, Quaestiones Math. (2020), DOI: 10.2989/16073606.2020.1785576] the authors proved two best proximity point theorems for a new class of non-self mappings, called interpolative Reich-Rus-Ćirić...
    View item »
  322. Closed-form solutions via the invariant approach for one-factor commodity models

    Closed-form solutions via the invariant approach for one-factor commodity models

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A.G. Johnpillai --- Eastern University, Sri Lanka F.M. Mahomed --- University of the Witwatersrand, South Africa
    We utilise the invariant method for scalar linear (1+1) parabolic partial differential equations so as to effect reductions via invertible transformations to Lie canonical forms of the first and third types. This is performed for the one-factor commodity models that...
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  323. Characterizations of maximal &lt;em&gt;z&lt;/em&gt;&deg;-ideals of &lt;em&gt;C&lt;/em&gt;(&lt;em&gt;X&lt;/em&gt;) and real maximal ideals of &lt;em&gt;q&lt;/em&gt;(&lt;em&gt;X&lt;/em&gt;)

    Characterizations of maximal z°-ideals of C(X) and real maximal ideals of q(X)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Z. Arjmandnezhad --- Shahid Chamran University of ahvaz, Iran F. Azarpanah --- Shahid Chamran University of ahvaz, Iran A.A. Hesari --- Shahid Chamran University of ahvaz, Iran A.R. Salehi --- Petroleum University of Technology, Iran
    In this paper we first give elementwise characterizations of real maximal ideals and maximal z°-ideals of C(X). Next, using this we characterize the real maximal ideals of the classical ring of quotients q(X) of C(X) and also maximal z°-ideals of...
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  324. On the parabolicity of linear Weingarten spacelike submanifolds in the de Sitter space

    On the parabolicity of linear Weingarten spacelike submanifolds in the de Sitter space

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Railane Antonia --- Universidade Federal da Para&iacute;ba, Brazil Henrique F. de Lima --- Universidade Federal de Campina Grande, Brazil
    In this paper, we deal with complete linear Weingarten spacelike sub-manifold immersed with parallel normalized mean curvature vector in de Sitter space of index p. Imposing appropriate restrictions on the values of the mean curvature function H, we establish a...
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  325. Extensions and dilations of module maps

    Extensions and dilations of module maps

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Massoud Amini --- Tarbiat Modares University, Iran
    We study completely positive module maps on C*-algebras which are C*-module over another C*-algebra with compatible actions. We extend several well known dilation and extension results to this setup, including the Stinespring dilation theorem and Wittstock, Arveson, and Voiculescu extension...
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  326. Commutation formulae with respect to non-symmetric affine connection

    Commutation formulae with respect to non-symmetric affine connection

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Du&scaron;an J. Simjanović --- Metropolitan University, Serbia Nenad O. Vesić --- Mathematical Institute, Serbia
    Commutation formulae with respect to a non-symmetric affine connection are obtained in this paper. The components of commutation formulae in this paper are covariant derivatives of tensors with respect to symmetric and non-symmetric affine connection.
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  327. A note on stabilisations of manifolds

    A note on stabilisations of manifolds

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Daniele Ettore Otera --- Vilnius University, Institute of Data Science and Digital Technologies, Lithuania
    In this short note we consider the relationships between two topological tameness condition at infinity of open manifolds in the case of product with a ball.
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  328. Helly-type results for 3-disjoint families of convex bodies in the plane

    Helly-type results for 3-disjoint families of convex bodies in the plane

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Zokhrab Mustafaev --- University of Houston-Clear Lake, USA Jamesley Norvil --- University of Houston-Clear Lake, USA
    In this note, we prove that a family of non-overlapping, 3-disjoint convex bodies in the plane with the property S(n) will also have the property S(n + 1) for n ≥ 5. This result leads confirming the conjecture of Revenko-Soltan.
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  329. Preenveloping classes of acts

    Preenveloping classes of acts

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mohanad Farhan Hamid --- University of Technology-Iraq, Iraq
    Preenvelopes of acts over a monoid are defined by analogy with Enochs’ definition of preenvelopes of modules. Provided that it is closed for pure subacts, a class of acts is shown to be preenveloping precisely when it is closed under...
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  330. Joint discrete universality for periodic zeta-functions. IV

    Joint discrete universality for periodic zeta-functions. IV

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Antanas Laurinčikas --- Vilnius University, Lithuania
    In the paper, a theorem on the approximation of collections of a wide class of analytic functions by collections of shifts of zeta-functions with periodic co-efficients involving imaginary parts of non-trivial zeros of the Riemann zeta-function is obtained. For this,...
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  331. Wardowski and Ćirić type fixed point theorems over non-triangular metric spaces

    Wardowski and Ćirić type fixed point theorems over non-triangular metric spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: V. Rakočević --- University of Ni&scaron;, Serbia K. Roy --- The University of Burdwan, India M. Saha --- The University of Burdwan, India
    In this manuscript, we establish a fixed point theorem for F -Suzuki contraction mapping over a non-triangular metric space and also give a discussion as remarks on the non-triangular metric structure. Moreover we introduce non-triangular metric-like space and prove a...
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  332. A look at the structure of congruence frames by means of Heyting congruences

    A look at the structure of congruence frames by means of Heyting congruences

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: John Frith --- University of Cape Town, South Africa Anneliese Schauerte --- University of Cape Town, South Africa
    This paper concerns the congruence frame in the setting of partial frames, which, in contrast to full frames, do not necessarily have all joins. Examples of these include bounded distributive lattices, σ- and κ-frames. A new class of congruences, called...
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  333. Height growth strategies of &lt;em&gt;Mimosa scabrella&lt;/em&gt; along a chronosequence

    Height growth strategies of Mimosa scabrella along a chronosequence

    Item type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: Vinicius Costa Cysneiros --- Federal University of Paran&aacute;, Brazil Sebasti&atilde;o do Amaral Machado --- Federal University of Paran&aacute;, Brazil Allan Libanio Pelissari --- Federal University of Paran&aacute;, Brazil Edilson Urbano --- State University of Mato Grosso do Sul, Aquidauana University Unit, Brazil
    Assessing variations in tree allometry is useful for understanding height growth strategies in relation to life-history trajectories, light competition and environmental restrictions. Scaling exponent and asymptotic heights obtained from height–diameter (HD) models may elucidate how trees optimise growth strategies and...
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  334. On rings related to filial and left filial rings

    On rings related to filial and left filial rings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: D.I.C. Mendes --- University of Beira Interior, Portugal
    A ring R is called filial (left weakly filial) if it satisfies the following condition: for all subrings J and I of R, if J is an ideal of I and I is an ideal of R, then J is...
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  335. The Laplace transform on the rearrangement of invariant spaces

    The Laplace transform on the rearrangement of invariant spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ren&eacute; Erlin Castillo --- Departamento de Matem&aacute;ticas Universidad Nacional de Colombia, Colombia A. Ricardo Miranda B. --- Departamento de Matem&aacute;ticas Universidad Nacional de Colombia, Colombia Julio C. Ramos-Fern&aacute;ndez --- Universidad Distrital Francisco Jos&eacute; de Caldas, Colombia
    In a self contained presentation we study the boundedness of the Laplace transform on the rearrangement invariant Lebesgue Lp -space, we use real analysis techniques provided by convex analysis and the K-method.
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  336. Hochschild cohomology of certain Koszul Sullivan Extensions

    Hochschild cohomology of certain Koszul Sullivan Extensions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jean Baptiste Gatsinzi --- Botswana International University of Science and Technology, Botswana Oteng Maphane --- Botswana International University of Science and Technology, Botswana
    We consider a totally non cohomologous to zero fibration , where B is an elliptic 2-stage Postnikov tower and a Koszul Sullivan model of p. In this paper, we show that the induced map in Hochschild cohomology HH*(f): HH*(∧V; ∧V...
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  337. On multipliers of pairs of Lie superalgebras

    On multipliers of pairs of Lie superalgebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Hesam Safa --- University of Bojnord, Iran
    We study the notion of the Schur multiplier of a pair (N, L) of Lie superalgebras and obtain some upper bounds concerning dimensions. Moreover, we characterize the pairs of finite dimensional (nilpotent) Lie superalgebras for which
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  338. Solvability and nilpotency of expanded groups relative to the nearring of zero and congruence preserving functions

    Solvability and nilpotency of expanded groups relative to the nearring of zero and congruence preserving functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Gary L. Peterson --- James Madison University, USA Stuart D. Scott --- University of Auckland, New Zealand
    In this paper we study solvability and nilpotency of an expanded group relative to the nearring of zero and congruence preserving functions of the expanded group. A particular case of interest is when the expanded group is a nearring module...
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  339. Modules whose exact submodules are essentially embedded in summands

    Modules whose exact submodules are essentially embedded in summands

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Fıgen Takıl Mutlu --- Eskisehir Technical University, Turkey Adnan Tercan --- Hacettepe University, Turkey Ramazan Yaşar --- Hacettepe University, Turkey
    In this article we study the condition that every exact submodule is essentially embedded in direct summands in a module. It is shown that the class of modules with former property is closed under direct sums. However, we provide examples...
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  340. Weak limited sets and operators on Banach lattices

    Weak limited sets and operators on Banach lattices

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Farid Afkir --- Moulay Isma&iuml;l University, Morocco Aziz Elbour --- Moulay Isma&iuml;l University, Morocco
    In this paper, we prove that an operator T : E → F , between two Banach lattices, maps order intervals onto weak limited sets if and only if the modulus |ST| exists and is Dunford-Pettis for every Dunford-Pettis operator...
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  341. Multidimensional Kantorovich modifications of exponential sampling series

    Multidimensional Kantorovich modifications of exponential sampling series

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Tuncer Acar --- Selcuk University, Turkey Sadettin Kursun --- Selcuk University, Turkey Metin Turgay --- Selcuk University, Turkey
    This paper is devoted to construction of multidimensional Kantorovich modifications of exponential sampling series, which allows to approximate suitable measurable functions by considering their mean values on just one section of the function involved. Approximation behaviour of newly constructed operators...
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  342. Remarks on star weakly Lindel&ouml;f spaces

    Remarks on star weakly Lindelöf spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Yan-Kui Song --- Nanjing Normal University, P.R. China Wei-Feng Xuan --- Nanjing Audit University, P.R. China
    Let P be a topological property. A space X is said to be star P if whenever is an open cover of X, there exists a subspace A ⊆ X with property P such that , where . In this...
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  343. Equivalent almost periodic functions in terms of the new property of almost equality

    Equivalent almost periodic functions in terms of the new property of almost equality

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Juan Mat&iacute;as Sepulcre --- University of Alicante, Spain Tom&aacute;s Vidal --- Universidad Nacional de Educaci&oacute;n a Distancia (UNED), Spain
    In this paper we introduce the notion of almost equality (or, more specifically, almost equality by translations) of complex functions of an unrestricted real variable in terms of the new concept of ϵ-translation number of a function with respect to...
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  344. Life skills training as HIV/AIDS preventive strategy in secondary schools: evaluation of a large-scale implementation process

    Life skills training as HIV/AIDS preventive strategy in secondary schools: evaluation of a large-scale implementation process

    Item type: Journal Article • Journal: SAHARA-J: Journal of Social Aspects of HIV/AIDS • Authors: Maretha J. Visser --- University of Pretoria,
    A life skills and HIV/AIDS education programme was implemented in secondary schools as a strategy to combat the spread of HIV/AIDS among school-going young people in South Africa. As part of a joint effort of the Departments of Health and...
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  345. Spatial and temporal distribution of call activities of two &lt;em&gt;Gephyromantis&lt;/em&gt; species (Mantellidae) along forest&ndash;farmbush habitat in Ranomafana, Madagascar

    Spatial and temporal distribution of call activities of two Gephyromantis species (Mantellidae) along forest–farmbush habitat in Ranomafana, Madagascar

    Item type: Journal Article • Journal: African Journal of Herpetology • Authors: Noelikanto Ramamonjisoa --- , , Madagascar Harisoa Rakotonoely --- , , Madagascar Hannah Thomas --- , Madagascar
    Understanding how changes in land use affect the distribution, abundance and behaviour of organisms is an increasingly important question in ecology. We investigated the distribution and the differential calling behaviour of two diurnal terrestrial frogs, Gephyromantis decaryi (Near Threatened) and...
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  346. A new insight to the Hamiltonian systems with a finite number of spectral parameters

    A new insight to the Hamiltonian systems with a finite number of spectral parameters

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ekin Uğurlu --- &Ccedil;ankaya University, Turkey
    In this article, we introduce a new first-order differential equation containing a finite number of spectral parameters and some results on the solutions of this equation. In particular, with the aid of the nested-circles approach we share a lower bound...
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  347. New approach to property (&lt;em&gt;&omega;&lt;/em&gt;) for functions of operators

    New approach to property (ω) for functions of operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Xiaohong Cao --- School of Mathematics and Statistics, Shaanxi Normal University, People&rsquo;s Republic of China Lili Yang --- School of Mathematics and Statistics, Shaanxi Normal University, People&rsquo;s Republic of China
    Let be an infinite dimensional complex Hilbert space and be the algebra of all bounded linear operators on . For , we say T satisfies property (ω) if σa (T) \ σea (T) = π 00(T), where π 00(T) =...
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  348. Further results on the independent Roman domination number of graphs

    Further results on the independent Roman domination number of graphs

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Abel Cabrera Mart&iacute;nez --- Universitat Rovira i Virgili, Spain Frank A. Hern&aacute;ndez Mira --- Universidad Aut&oacute;noma de Guerrero, M&eacute;xico
    Let f : V (G) → {0, 1, 2} be a function on a graph G with vertex set V (G). Let Vi = {v ∈ V (G) : f (v) = i} for every i ∈ {0, 1, 2}...
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  349. On norm-attainment in (symmetric) tensor products

    On norm-attainment in (symmetric) tensor products

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sheldon Dantas --- Universitat Jaume I, Spain Luis C. Garc&iacute;a-Lirola --- Universidad de Zaragoza, Spain Mingu Jung --- POSTECH, Republic of Korea Abraham Rueda Zoca --- Universidad de Murcia, Spain
    In this paper, we introduce a concept of norm-attainment in the projective symmetric tensor product of a Banach space X, which turns out to be naturally related to the classical norm-attainment of N -homogeneous polynomials on X. Due to this...
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  350. Eigenvalues of Sturm-Liouville problems with distributional potentials and eigenparameter-dependent boundary conditions

    Eigenvalues of Sturm-Liouville problems with distributional potentials and eigenparameter-dependent boundary conditions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ji-Jun Ao --- Inner Mongolia University of Technology, China Meng-Lei Li --- Inner Mongolia University of Technology, China Hai-Yan Zhang --- Inner Mongolia University of Technology, China
    In this paper, regular Sturm-Liouville problems with distributional potentials and eigenparameter-dependent boundary conditions are investigated. We obtain that the eigenvalues of the problems depend not only continuously but also smoothly on the parameters of the problem: the coefficients, the boundary...
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  351. New parity results for 3-regular partitions

    New parity results for 3-regular partitions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Olivia X.M. Yao --- Suzhou University of Science and Technology, P.R. China
    Let bt (n) count the number of t-regular partitions of n. In recent years, congruence properties of bt (n) have received a lot of attention and a number of infinite families of congruences modulo 2 for bt (n) have been...
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  352. Linear equivalence of (pseudo) compact spaces

    Linear equivalence of (pseudo) compact spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jan Baars --- , Singapore Jan van Mill --- KdV Institute for Mathematics, University of Amsterdam, The Netherlands Vladimir V. Tkachuk --- Universidad Aut&oacute;noma Metropolitana, Mexico
    Given Tychonoff spaces X and Y, Uspenskij proved in [15] that if X is pseudocompact and Cp(X) is uniformly homeomorphic to Cp (Y), then Y is also pseudocompact. In particular, if Cp (X) is linearly homeomorphic to Cp (Y), then...
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  353. A note on &lt;em&gt;p&lt;/em&gt;-adic Raabe formulas

    A note on p-adic Raabe formulas

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Min-Soo Kim --- Kyungnam University, Republic of Korea
    The Hurwitz-type Euler (or the alternating Hurwitz) zeta function is defined by the following series
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  354. Comultiplication structures on the wedge product of spheres

    Comultiplication structures on the wedge product of spheres

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Dae-Woong Lee --- Jeonbuk National University, Republic of Korea Sunyoung Lee --- Jeonbuk National University, Republic of Korea
    Homotopy multiplications on H-spaces and homotopy comultiplications on co-H-spaces play an important role in topology for many reasons. They are the duals with each other in the sense of Eckmann and Hilton, and have many kinds of examples to construct...
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  355. Mixed Nash equilibria for continuous games and reverse mathematics

    Mixed Nash equilibria for continuous games and reverse mathematics

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: NingNing Peng --- Wuhan University of Technology, China Weiguang Peng --- Southwest University, China Takeshi Yamazaki --- Tohoku University, Japan
    The program reverse mathematics seeks to identify the minimal axioms needed to prove theorems of ordinary mathematics. In this paper, we develop the reverse mathematics of measure theory and apply these results to the reverse mathematics study of game theory...
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  356. Reciprocity of the Wigner derivative for spherical tetrahedra

    Reciprocity of the Wigner derivative for spherical tetrahedra

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Bruce Bartlett --- Stellenbosch University, V. Hosana Ranaivomanana --- Stellenbosch University,
    The Wigner derivative is the partial derivative of dihedral angle with respect to opposite edge length in a tetrahedron, all other edge lengths remaining fixed. We compute the inverse Wigner derivative for spherical tetrahedra, namely the partial derivative of edge...
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  357. Blow-up of solutions for a wave equation with nonlinear averaged damping and nonlocal nonlinear source terms

    Blow-up of solutions for a wave equation with nonlinear averaged damping and nonlocal nonlinear source terms

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Qingying Hu --- Henan University of Technology, China Donghao Li --- Henan University of Technology, China Shuo Liu --- Henan University of Technology, China Hongwei Zhang --- Henan University of Technology, China
    The initial-boundary value problem for a wave equation with nonlinear averaged damping and nonlocal nonlinear source term is considered. We provide the sufficient conditions of finite time blow-up for weak solutions with suitable conditions on initial data by an ordinary...
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  358. On 0012-avoiding inversion sequences and a conjecture of Lin and Ma

    On 0012-avoiding inversion sequences and a conjecture of Lin and Ma

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Shane Chern --- Dalhousie University, Canada
    The study of pattern avoidance in inversion sequences recently attracts extensive research interests. In particular, Zhicong Lin and Jun Ma conjectured a formula that counts the number of inversion sequences avoiding the length-four pattern 0012. Our object of the paper...
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  359. On the block functions generating the limit &lt;em&gt;q&lt;/em&gt;-Lupaş operator

    On the block functions generating the limit q-Lupaş operator

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sofiya Ostrovska --- Atilim University, Turkey Mehmet Turan --- Atilim University, Turkey
    The limit q-Lupaş operator emerged in the study of the Lupaş q-analogue of the Bernstein operator. Afterward, it has been found that it is connected to numerical analysis, computer aided geometric design, probability theory and other areas. In this paper,...
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  360. More on cardinality bounds involving the weak Lindel&ouml;f degree

    More on cardinality bounds involving the weak Lindelöf degree

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Bella --- University of Catania, Italy N. Carlson --- California Lutheran University, USA I. Gotchev --- Central Connecticut State University, USA
    We give several new bounds for the cardinality of a Hausdorff topological space X involving the weak Lindelöf degree ωL(X). In particular, we show that if X is extremally disconnected, then |X| ≤ 2 ωL (X)πχ(X)ψ(X), and if X...
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  361. Eliahou number, Wilf function and concentration of a numerical semigroup

    Eliahou number, Wilf function and concentration of a numerical semigroup

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Patricio Almir&oacute;n --- Universidad Complutense de Madrid, Spain Julio Jos&eacute; Moyano-Fern&aacute;ndez --- Departamento de Matem&aacute;ticas &amp; Institut Universitari de Matem&aacute;tiques i Aplicacions de Castell&oacute;, Spain
    We give an estimate of the minimal positive value of the Wilf function of a numerical semigroup in terms of its concentration. We describe necessary conditions for a numerical semigroup to have a negative Eliahou number in terms of its...
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  362. On bases of closure operators on complete lattices

    On bases of closure operators on complete lattices

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Josef &Scaron;lapal --- Brno University of Technology, Institute of Mathematics, Czech Republic
    We study closure operators on complete lattices and define for them the concepts of closed and open bases as well as that of a neighborhood base. Some properties of these concepts are studied including relationships between them. In particular, we...
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  363. Nonmeasurable Vitali set: variations on theme

    Nonmeasurable Vitali set: variations on theme

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Angelo Bella --- University of Catania, Italy (EU) Daniele Puglisi --- University of Catania, Italy (EU) Alfonso Villani --- University of Catania, Italy (EU)
    We extend Vitali’s procedure to get nonmeasurable sets. Answering a question of Kharazishvili [4], we present a relatively simple argument for passing from singletons to finite sets. Our result is actually much stronger, as it covers even the case of...
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  364. Boundedness of the Hilbert transform in Lorentz spaces and applications to operator ideals

    Boundedness of the Hilbert transform in Lorentz spaces and applications to operator ideals

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: K.S. Tulenov --- Al-Farabi Kazakh National University, Kazakhstan
    In this paper, it is investigated the optimal range of the classical Hilbert transform in Lorentz spaces of functions and its non-commutative counterparts including a triangular truncation operator in Schatten-Lorentz ideals. Some applications of obtained results to operator Lipschitz functions...
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  365. Initial boundary value problem for a damped wave equation with logarithmic nonlinearity

    Initial boundary value problem for a damped wave equation with logarithmic nonlinearity

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Haixia Li --- Changchun Normal University, P.R. China
    In this paper, a damped semilinear wave equation with logarithmic non-linearity is considered. Finite time blow-up criteria are established for solutions with both lower and higher initial energy, and an upper bound for the blow-up time is derived for each...
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  366. The weight distribution of hulls of binary codes from incidence matrices of complete graphs

    The weight distribution of hulls of binary codes from incidence matrices of complete graphs

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Khumbo Kumwenda --- Mzuzu University, Malawi Caleb Namondwe --- Mzuzu University, Malawi
    We characterise the weights of all codewords of the hull of the binary code spanned by rows of an incidence matrix Bn of the complete graph Kn for n ≥ 4 and n even. Among others, we show that every...
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  367. On a functional identity involving inverses on matrix rings

    On a functional identity involving inverses on matrix rings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Nadeem Ahmad Dar --- Government HSS, India Wu Jing --- Fayetteville State University, USA
    Let be a division ring which is not a field with characteristic different from 2 and 3, and with n > 1. The purpose of this paper is to characterize additive maps f,g : satisfying the functional identity f(X) +...
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  368. Representation theorems for closed ideals of &lt;em&gt;C&lt;sub&gt;B&lt;/sub&gt; &lt;/em&gt;(&lt;em&gt;X&lt;/em&gt;)

    Representation theorems for closed ideals of CB (X)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Alireza Olfati --- Yasouj University, Iran
    Let CB (X) be the Banach algebra of all continuous bounded ℂ-valued functions on a completely regular Hausdorff space X equipped with the supremum norm. We provide representation theorems for arbitrary closed ideals of CB (X). Indeed, for a closed...
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  369. On localization of the Menger property

    On localization of the Menger property

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Nur Alam --- University of Gour Banga, India Debraj Chandra --- University of Gour Banga, India
    In this paper we introduce and study the local version of the Menger property, namely locally Menger property (or, locally Menger space). We explore some preservation like properties in this space. We also discuss certain situations where this local property...
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  370. On total domination and minimum maximal matchings in graphs

    On total domination and minimum maximal matchings in graphs

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Selim Bahadır --- Ankara Yıldırım Beyazıt University, Turkey
    A subset M of the edges of a graph G is a matching if no two edges in M are incident. A maximal matching is a matching that is not contained in a larger matching. A subset S of vertices...
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  371. A family of congruent number elliptic curves of rank three

    A family of congruent number elliptic curves of rank three

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Lorenz Halbeisen --- , Switzerland Norbert Hungerb&uuml;hler --- , Switzerland Arman Shamsi Zargar --- University of Mohaghegh Ardabili, Iran
    Recent progress in the theory of Heron triangles and their elliptic curves led to new families of congruent number elliptic curves with rank at least two. Based on these results, we derive a parametric family of congruent number elliptic curves...
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  372. Some further remarks on characterized subgroups generated by modular simple density

    Some further remarks on characterized subgroups generated by modular simple density

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ayan Ghosh --- Jadavpur University, India
    In this short note we have constructed an uncountable tower of characterized subgroups using the notion of modular simple density [8] which subsequently gives the solution of Problem 2.15 [7] in a more general setting.
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  373. On the categorical behaviour of locales and &lt;em&gt;D&lt;/em&gt;-localic maps

    On the categorical behaviour of locales and D-localic maps

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Igor Arrieta --- University of Coimbra, Portugal Javier Guti&eacute;rrez Garc&iacute;a --- University of the Basque Country UPV/EHU, Spain
    It was shown by Banaschewski and Pultr that the classical adjunction between Top and Loc restricts to an adjunction between the category Top D of TD -spaces and their continuous maps, and the category Loc D of all locales and...
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  374. Some sharpened and refined versions of the &lt;em&gt;q&lt;/em&gt;&mdash;Steffensen inequality

    Some sharpened and refined versions of the q—Steffensen inequality

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ksenija Smoljak Kalamir --- University of Zagreb, Croatia
    Based on a known sharpened and refined versions of a classical Steffensen inequality, we derive new sharpened and refined versions of a q–Steffensen inequality. Next, we give weaker conditions for some already known generalizations of q–Steffensen’s inequality and for new...
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  375. Set-valued solutions of an equation of Jensen type

    Set-valued solutions of an equation of Jensen type

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Alina Ramona Baias --- Technical University of Cluj-Napoca, Romania Dorian Popa --- Technical University of Cluj-Napoca, Romania Michael Th. Rassias --- Institute of Mathematics, University of Zurich, Switzerland
    In this paper we provide a characterization theorem for set-valued solutions of the functional equation for the case of compact, convex valued maps. We prove that every solution of the functional equation is the sum of an additive single-valued function...
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  376. On exactness and homology of hyperchain complexes

    On exactness and homology of hyperchain complexes

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Asieh Pourhaghani --- Ferdowsi University of Mashhad, Iran Hamid Torabi --- Ferdowsi University of Mashhad, Iran
    In this paper we define the concepts of a “strict morphism” as a suitable map between geometric spaces (as a generalization of hyperstructures), and its kernel. Then we introduce the concepts of a “quotient geometric space”, an “exact sequence”, an...
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  377. Representable and Radon-Nikod&yacute;m polynomials

    Representable and Radon-Nikodým polynomials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Raffaella Cilia --- Universit&agrave; di Catania, Italy Joaqu&iacute;n M. Guti&eacute;rrez --- Universidad Polit&eacute;cnica de Madrid, Spain
    Every k-homogeneous (continuous) polynomial between Banach spaces admits a unique Aron-Berner extension to the biduals.
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  378. Nonlinear maps preserving semi-Fredholm operators with bounded nullity

    Nonlinear maps preserving semi-Fredholm operators with bounded nullity

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Guoxing Ji --- Shaanxi Normal University, People&rsquo;s Republic of China Xia Jiao --- Shaanxi Normal University, People&rsquo;s Republic of China Weijuan Shi --- Shaanxi Normal University, People&rsquo;s Republic of China
    Let be an infinite dimensional complex Banach space, and let be the algebra of all bounded linear operators on . In this paper, given any positive integer n, we provide a characterization of all bijective maps on preserving the difference...
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  379. On Yang-Baxter groups

    On Yang-Baxter groups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Ballester-Bolinches --- Guangdong University of Education, People&rsquo;s Republic of China R. Esteban-Romero --- Universitat de Val&egrave;ncia, Spain P. Jim&eacute;nez-Seral --- Universidad de Zaragoza, Spain V. P&eacute;rez-Calabuig --- Universitat de Val&egrave;ncia, Spain
    A group is said to be an involutive Yang-Baxter group, or simply an IYB-group, if it is isomorphic to the permutation group of an involutive, non-degenerate set-theoretic solution of the Yang-Baxter equation. In this paper, Yang-Baxter groups (YB-groups for short)...
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  380. On the coincidence of automorphism groups of finite &lt;em&gt;p&lt;/em&gt;-groups

    On the coincidence of automorphism groups of finite p-groups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Rohit Garg --- Govt. Ripudaman College, India Mandeep Singh --- Arya College, India
    Let G be a finite non-abelian p-group, where p is a prime. Let γn (G) and Zn (G) respectively denote the nth term of the lower and upper central series of G, and let Ln (G) denote the nth absolute...
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  381. Inverses and order boundedness of invertible ideal operators

    Inverses and order boundedness of invertible ideal operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Kazım &Ouml;zcan --- , Turkey Bahri Turan --- Gazi University, Turkey
    In this paper, we investigate that under which conditions the inverse of an invertible ideal operator becomes an ideal operator. To determine conditions, in the first case, we consider the center of a Riesz space and achieve the solution by...
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  382. Connectedness modulo an ideal; a characterization theorem

    Connectedness modulo an ideal; a characterization theorem

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M.R. Koushesh --- Isfahan University of Technology, Iran
    Let X be a topological space and let be an ideal of subsets of X. The space X is called connected modulo if there is no continuous mapping f : X → [0, 1] which is 2-valued modulo in the...
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  383. On the extent of the injectivity of direct sums of modules

    On the extent of the injectivity of direct sums of modules

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sergio R. L&oacute;pez-Permouth --- Ohio University, USA B&uuml;lent Sara&ccedil; --- Hacettepe University, Turkey
    Inspired by the fact that a ring is right Noetherian if and only if direct sums of certain injective right modules are once again injective, we propose a way to not only decide whether a ring is Noetherian but to...
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  384. On uniform &lt;em&gt;f&lt;/em&gt; &minus;statistical convergence of sequences of functions

    On uniform f −statistical convergence of sequences of functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M.C. List&aacute;n-Garc&iacute;a --- Universidad de C&aacute;diz, Spain
    We introduce the notions of uniform f −statistical convergence of sequences and uniform f −statistical Cauchy sequences of functions. The natural equivalence between these two notions, in Banach spaces, is proved. In doing so, we generalize and improve results of...
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  385. A generalization of Taketa&rsquo;s theorem on M-groups

    A generalization of Taketa’s theorem on M-groups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Zeinab Akhlaghi --- Amirkabir University of Technology (Tehran Polytechnic), Iran
    Let G be a finite group. We prove the solvability of G, by assuming that the average degree of non-monomial irreducible characters in Irr(G) is less than 5/2. The bound is sharp.
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  386. Oscillation criteria for noncanonical neutral Emden-Fowler differential equations

    Oscillation criteria for noncanonical neutral Emden-Fowler differential equations

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Orhan &Ouml;zdemir --- Tokat Gaziosmanpasa University, Turkey
    This study purposes to present some new sufficient conditions for the oscillation of all solutions to a second order noncanonical Emden-Fowler differential equation with mixed neutral term i.e., the neutral term contains both retarded and advanced arguments. The obtained results...
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  387. On dual-classical Krull dimension of rings

    On dual-classical Krull dimension of rings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sayed Malek Javdannezhad --- Shahid Rajaee Teacher Training University, Iran Sayedeh Fatemeh Mousavinasab --- Shahid Chamran University of Ahvaz, Iran Nasrin Shirali --- Shahid Chamran University of Ahvaz, Iran
    An ideal L of a ring R is said to be strongly hollow (briefly, sh-ideal) if L ⊆ A + B implies that either L ⊆ A or L ⊆ B, for every pair A and B of ideals of...
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  388. Pre-rigid monoidal categories

    Pre-rigid monoidal categories

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Alessandro Ardizzoni --- University of Turin, Italy Isar Goyvaerts --- Vrije Universiteit Brussel, Claudia Menini --- University of Ferrara, Italy
    Liftable pairs of adjoint functors between braided monoidal categories in the sense of [GV1] provide auto-adjunctions between the associated categories of bialgebras. Motivated by finding interesting examples of such pairs, we study general pre-rigid monoidal categories. Roughly speaking, these are...
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  389. On central automorphisms of finite &lt;em&gt;p&lt;/em&gt;-groups of class 2

    On central automorphisms of finite p-groups of class 2

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M. Shabani-Attar --- Payame Noor University, Iran
    Let G be a finite p-group and let Aut c (G) be the group of all central automorphisms of G. Let be the set of all central automorphisms of G fixing Z(G) elementwise. For a finite p-group of class 2,...
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  390. The integer sequence transform &lt;em&gt;a&lt;/em&gt; &rarr; &lt;em&gt;b&lt;/em&gt;, where &lt;em&gt;b&lt;sub&gt;n&lt;/sub&gt; &lt;/em&gt; is the number of real roots of the polynomial &lt;em&gt;a&lt;/em&gt; &lt;sub&gt;0&lt;/sub&gt; + &lt;em&gt;a&lt;/em&gt; &lt;sub&gt;1&lt;/sub&gt; &lt;em&gt;x&lt;/em&gt; + &lt;em&gt;a&lt;/em&gt; &lt;sub&gt;2&lt;/sub&gt; &lt;em&gt;x&lt;/em&gt; &lt;sup&gt;2&lt;/sup&gt; + &lt;em&gt;&middot; &middot; &middot;&lt;/em&gt; + &lt;em&gt;a&lt;sub&gt;n&lt;/sub&gt;x&lt;sup&gt;n&lt;/sup&gt; &lt;/em&gt;

    The integer sequence transform a → b, where bn is the number of real roots of the polynomial a 0 + a 1 x + a 2 x 2 + · · · + anxn

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: W. Edwin Clark --- University of South Florida, USA Mark Shattuck --- University of Tennessee, USA
    We discuss the integer sequence transform a 1→ b, where bn is the number of real roots of the polynomial a 0 + a 1 x + a 2 x 2 + · · · + anxn . It is...
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  391. &lt;inline-formula&gt; &lt;mml:math&gt; &lt;mml:msubsup&gt; &lt;mml:mi&gt;L&lt;/mml:mi&gt; &lt;mml:mi&gt;&omega;&lt;/mml:mi&gt; &lt;mml:mn&gt;1&lt;/mml:mn&gt; &lt;/mml:msubsup&gt; &lt;/mml:math&gt; &lt;/inline-formula&gt;-invariant weighted Orlicz spaces

    L ω 1 -invariant weighted Orlicz spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: AliReza Bagheri Salec --- University of Qom, Iran Seyyed Mohammad Tabatabaie --- University of Qom, Iran
    In this paper, we prove that σ-compactness of a locally compact group G is a necessary condition for the weighted Orlicz space to be a convolution algebra, and for a class of Orlicz spaces we give an equivalent condition. Also,...
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  392. An inverse source problem for a nonlinear pseudoparabolic equation with p-Laplacian diffusion and damping term

    An inverse source problem for a nonlinear pseudoparabolic equation with p-Laplacian diffusion and damping term

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Khonatbek Khompysh --- Al-Farabi Kazakh National University, Kazakhstan Aidos Ganizhanuly Shakir --- Al-Farabi Kazakh National University, Kazakhstan
    In this work, we study the unique solvability of the inverse problem that consists of determining a weak solution u(x, t) to the nonlinear pseudoparabolic equation with p−Laplacian and damping term
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  393. Equivalent version of Huppert&rsquo;s conjecture for codegrees of &lt;em&gt;K&lt;/em&gt; &lt;sub&gt;3&lt;/sub&gt;-groups

    Equivalent version of Huppert’s conjecture for codegrees of K 3-groups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mohsen Ghasemi --- Urmia University, Iran Somayeh Hekmatara --- Urmia University, Iran
    For a character χ of a finite group G the number cod(χ) = |G: Ker(χ)|/χ(1) is called the codegree of χ. In this note, we verify the equivalent version of Huppert’s conjecture for K 3 -groups.
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  394. Approximate controllability of non-instantaneous impulsive semi-linear neutral differential equations with non-local conditions and unbounded delay

    Approximate controllability of non-instantaneous impulsive semi-linear neutral differential equations with non-local conditions and unbounded delay

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Oscar Camacho --- Universidad San Francisco de Quito USFQ, Ecuador S. Lalvay-Segovia --- , Ecuador Hugo Leiva --- , Ecuador L. Riera-Segura --- , Ecuador
    In this work, we study the approximate controllability for retarded neutral differential equations with unbounded delay, non-instantaneous impulses, and non-local conditions. First, we set the problem in a natural Banach phase space satisfying Hale-Kato axiomatic Theory about the phase space...
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  395. Depth of &lt;em&gt;C&lt;/em&gt;(&lt;em&gt;X&lt;/em&gt;)-modules

    Depth of C(X)-modules

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: F. Azarpanah --- Shahid Chamran University of ahvaz, Iran A.A. Hesari --- Shahid Chamran University of ahvaz, Iran A.R. Salehi --- Petroleum University of Technology, Iran
    It is shown that the depth of every module over C(X), the ring of all real valued continuous functions on a topological space X, is at most 1. This result is proved for modules over rings of a much more...
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  396. Universal specialization semilattices

    Universal specialization semilattices

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Paolo Lipparini --- Universit&agrave; di Roma &ldquo;Tor Vergata&rdquo;, Italy
    A specialization semilattice is a structure which can be embedded into , where X is a topological space, x ⊑ y means x ⊆ Ky, for x, y ⊆ X, and K is closure in X. Specialization semilattices and posets...
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  397. The (&lt;em&gt;E&lt;/em&gt;, &lt;em&gt;E&lt;/em&gt;)-approximation property for Banach spaces

    The (E, E)-approximation property for Banach spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ju Myung Kim --- Sejong University, Korea Bentuo Zheng --- The University of Memphis, USA
    For a given Banach space E with an 1-unconditional basis, we introduce the (E, E)-approximation property ((E, E)-AP) which is a natural generalization of the classical approximation property (AP) and the (p, p)-AP. It is shown that the AP always...
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  398. On the cubic Pell equation over finite fields

    On the cubic Pell equation over finite fields

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Simone Dutto --- , Italy Nadir Murru --- Universit&agrave; degli Studi di Trento, Italy
    The classical Pell equation can be extended to the cubic case considering the elements of norm one in , which satisfy
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  399. A note on &lt;em&gt;J&lt;/em&gt; -spaces and relatively connected subsets

    A note on J -spaces and relatively connected subsets

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Simo S. Mthethwa --- University of KwaZulu-Natal, South Africa Ali Taherifar --- Yasouj University, Iran
    In this note we present an investigation of J -spaces and other types of spaces related to J -spaces. We characterise these spaces using the notion of relatively connected subsets. For a completely regular J -space X, we give a...
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  400. Haagerup property of semigroup crossed products

    Haagerup property of semigroup crossed products

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Qing Meng --- Qufu Normal University, China
    In this paper, we study the Haagerup property of semigroup crossed products for lattice ordered groups. Let G be a lattice ordered group. We show that the reduced semigroup C*-algebra C*r (G +) has the Haagerup property if and only...
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  401. A pointfree theory of Pervin spaces

    A pointfree theory of Pervin spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: C&eacute;lia Borlido --- Centre for Mathematics of the University of Coimbra (CMUC), Portugal Anna Laura Suarez --- Universit&eacute; Nice Sophia Antipolis, France
    We lay down the foundations for a pointfree theory of Pervin spaces. A Pervin space is a set equipped with a bounded sublattice of its powerset, and it is known that these objects characterize those quasi-uniform spaces that are transitive...
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  402. Twisted sums of &lt;em&gt;c&lt;/em&gt; &lt;sub&gt;0&lt;/sub&gt;(&lt;em&gt;I&lt;/em&gt;)

    Twisted sums of c 0(I)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jess&uacute; M.F. Castillo --- Universidad de Extremadura, Instituto de Matem&aacute;ticas Imuex, Spain Alberto Salguero Alarc&oacute;n --- Universidad de Extremadura, Instituto de Matem&aacute;ticas Imuex, Spain
    We study in this paper a few remarkable properties of twisted sums Z(κ, X) of c 0(κ) and a Banach space X. We first prove a representation theorem for such twisted sums from which we will obtain, among others, the...
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  403. Equidivisibility and profinite coproduct

    Equidivisibility and profinite coproduct

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jorge Almeida --- Universidade do Porto, Portugal Alfredo Costa --- University of Coimbra, Portugal
    The aim of this work is to investigate the behavior of equidivisibility under coproduct in the category of pro-V semigroups, where V is a pseudovariety of finite semigroups. Exploring the relationship with the two-sided Karnofsky-Rhodes expansion, the notions of KR-cover...
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  404. Numerical radius inequalities for the off-diagonal parts of 2 &times; 2 operator matrices

    Numerical radius inequalities for the off-diagonal parts of 2 × 2 operator matrices

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Aicha Ammar --- Mustapha Stambouli University, Algeria Abdelkader Frakis --- Mustapha Stambouli University, Algeria Fuad Kittaneh --- The University of Jordan, Jordan
    We give some new bounds for the numerical radii of the off-diagonal parts of 2 × 2 operator matrices. A refinement of the triangle inequality for the operator norm is also given.
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  405. On set star-Menger spaces

    On set star-Menger spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sumit Singh --- University of Delhi, India
    In this paper, we prove that the product of a set star-Menger space with a compact space is a rectangular set star-Menger. We also provide an example of Tychonoff pesudocompact set star-Menger space which is not set strongly star-Menger. The...
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  406. Restricted inversion sequences and Schr&ouml;der paths

    Restricted inversion sequences and Schröder paths

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: David Callan --- University of Wisconsin-Madison, USA Toufik Mansour --- University of Haifa, Israel
    In this paper, we find an explicit formula for the number of inversion sequences of length n that avoid each of the pattern sets {021, 010}, {021, 011}, {021, 100, 101}, {021, 000, 101}, and {101, 102, 201}. This is...
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  407. Magnesium and zinc fertilisation improves rice yield and yield component responses to nitrogen, phosphorus, and potassium

    Magnesium and zinc fertilisation improves rice yield and yield component responses to nitrogen, phosphorus, and potassium

    Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: Firmin N Anago --- University of Abomey-Calavi, Benin Emile C Agbangba --- University of Abomey-Calavi, Benin Brice C T Oussou --- National Institute of Agronomic Research of Benin, Benin Gustave D Dagb&eacute;nonbakin --- National Institute of Agronomic Research of Benin, Benin Lucien G Amadji --- University of Abomey-Calavi, Benin
    The aim of this study was to assess the effects of magnesium (Mg) and zinc (Zn) on the response of rice to nitrogen (N), phosphorus (P), and potassium (K) application. Two sets of field experiments were carried out in Benin...
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  408. Epimorphisms and closure operators of categories of semilattices

    Epimorphisms and closure operators of categories of semilattices

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: D. Dikranjan --- Universit&agrave; degli Studi di Udine, Italy A. Giordano Bruno --- Universit&agrave; degli Studi di Udine, Italy N. Zava --- Institute of Science and Technology Austria (ISTA),
    Motivated by a problem posed in [10], we investigate the closure operators of the category SLatt of join semilattices and its subcategory SLatt O of join semilattices with bottom element. In particular, we show that there are only finitely many...
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  409. A characterization of derivations of JSL algebras

    A characterization of derivations of JSL algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Lin Chen --- Changshu Institute of Technology, P.R. China Jun Li --- Changshu Institute of Technology, P.R. ChinaChina Zijie Qin --- Changshu Institute of Technology, P.R. ChinaChina
    Let be a -subspace lattice algebra on a Banach space X and Inv() be the set of all invertible elements of . Suppose that δ : → is a linear mapping satisfying δ(A) ◦ A −1 + A ◦ δ(A...
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  410. On numerical invariants of a finite group factorized by tcc-subgroups

    On numerical invariants of a finite group factorized by tcc-subgroups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Alexander Trofimuk --- Brest State A.S. Pushkin University, Belarus
    A subgroup A of a group G is called tcc-subgroup in G, if there is a subgroup T of G such that G = AT and for any X ≤ A and for any Y ≤ T there exists an...
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  411. Counting covered fixed points and covered arcs in an involution

    Counting covered fixed points and covered arcs in an involution

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ronit Mansour --- , Israel
    An involution on [n] = {1, 2,…, n} is a permutation π 1 π 2… π n on [n] such that π πi = i for all i ∈ [n]. Let π = π 1 π 2 n be...
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  412. A generalization of the equation (2&lt;em&gt; &lt;sup&gt;k&lt;/sup&gt; &lt;/em&gt; &minus; 1) (3&lt;em&gt; &lt;sup&gt;l&lt;/sup&gt; &lt;/em&gt; &minus; 1) = 5&lt;em&gt; &lt;sup&gt;m&lt;/sup&gt; &lt;/em&gt; &minus; 1

    A generalization of the equation (2 k − 1) (3 l − 1) = 5 m − 1

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Nurettin Irmak --- Konya Technical University, Turkey
    Recently, Luca and Szalay solved the equation
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  413. Extension of semi-Lipschitz maps on non-subadditive quasi-metric spaces: new tools for Artificial Intelligence

    Extension of semi-Lipschitz maps on non-subadditive quasi-metric spaces: new tools for Artificial Intelligence

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Roger Arnau --- Instituto Universitario de Matem&aacute;tica Pura y Aplicada, Universitat Polit&egrave;cnica de Val&egrave;ncia, Spain Natalia Jonard-P&eacute;rez --- Universidad Nacional Aut&oacute;noma de M&eacute;xico, M&eacute;xico Enrique A. S&aacute;nchez P&eacute;rez --- Instituto Universitario de Matem&aacute;tica Pura y Aplicada, Universitat Polit&egrave;cnica de Val&egrave;ncia, Spain
    The axioms of symmetry and indiscernibility of a metric function can be eliminated and still define a topological space with good enough properties. However, among all the axioms that constitute the notion of a metric, the subadditivity or triangular inequality...
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  414. On the &lt;em&gt;L&lt;sub&gt;p&lt;/sub&gt; &lt;/em&gt;-sine moment-entropy inequality

    On the Lp -sine moment-entropy inequality

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Zi-Xin Cao --- Shaanxi Normal University, China Qingzhong Huang --- Jiaxing University, China Ai-Jun Li --- Zhejiang University of Science and Technology, China
    In this paper, we establish a sine version of the moment-entropy inequality due to Lutwak et al. [8]. Moreover, we show that this inequality is equivalent to the Lp -sine moment-entropy inequality recently established in [6].
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  415. On &lt;em&gt;b&lt;/em&gt;-repdigits as product of consecutive of Lucas members

    On b-repdigits as product of consecutive of Lucas members

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Kou&egrave;ssi Norbert Ad&eacute;dji --- Institut de Math&eacute;matiques et de Sciences Physiques, Universit&eacute; d&rsquo;Abomey-Calavi, B&eacute;nin Virgile Dossou-yovo --- Institut de Math&eacute;matiques et de Sciences Physiques, Universit&eacute; d&rsquo;Abomey-Calavi, B&eacute;nin Salah Eddine Rihane --- , Algeria Alain Togb&eacute; --- Purdue University Northwest, USA
    A b-repdigit is a positive integer that has only one distinct digit in its base b expansion, i.e. a number of the form a(bm – 1)=(b – 1), for some positive integers m ≥ 1, b ≥ 2 and 1...
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  416. On a comparison between absolute and relative self-adjoint extension schemes

    On a comparison between absolute and relative self-adjoint extension schemes

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: No&egrave; Angelo Caruso --- Mathematical Institute, Silesian University in Opava, Czech Republic Alessandro Michelangeli --- Prince Mohammad Bin Fahd University, Saudi Arabia Andrea Ottolini --- University of Washington, USA
    The problem of connecting the operator parameters that label the same self-adjoint extension of a given symmetric operator, respectively, within the ‘absolute’ von Neumann extension scheme and the ‘relative’ boundary-triplet-induced extension scheme (i.e., a la Kreĭn-Višik-Birman) is discussed, and quantitative...
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  417. The order bidual of C(&lt;em&gt;X&lt;/em&gt;) for a realcompact space

    The order bidual of C(X) for a realcompact space

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Marcel de Jeu --- Mathematical Institute, Leiden University, the Netherlands Jan Harm van der Walt --- University of Pretoria, South Africa
    It is well known that the bidual of C(X) for a compact space X, supplied with the Arens product, is isometrically isomorphic as a Banach algebra to for some compact space . The space is unique up to homeomorphism. We...
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  418. The modulus of a vector measure

    The modulus of a vector measure

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ben de Pagter --- Delft University of Technology, The Netherlands Werner J. Ricker --- Katholische Universit&auml;t Eichst&auml;tt-Ingolstadt, Germany
    It is known that if L is a Dedekind complete Riesz space and (Ω, Σ) is a measurable space, then the partially ordered linear space of all L-valued, finitely additive and order bounded vector measures m on Σ is also...
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  419. Remarks on weak compactness criteria in variable exponent Lebesgue spaces

    Remarks on weak compactness criteria in variable exponent Lebesgue spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Francisco L. Hern&aacute;ndez --- Complutense University of Madrid, Spain C&eacute;sar Ruiz --- Complutense University of Madrid, Spain Mauro Sanchiz --- Complutense University of Madrid, Spain
    We give two weak compactness Andô type criteria in variable exponent Lebesgue spaces Lp (·) (Ω) on infinite measures. This extends some results of [13] given in the case of finite measures. Spaces Lp (·) (Ω) on infinite measures are...
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  420. On a special Kapteyn series

    On a special Kapteyn series

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A.J.E.M. Janssen --- Eindhoven University of Technology, The Netherlands
    We investigate the mathematical properties of the function , ϵ ∈ [−1, 1], which is a special Kapteyn series of the first kind. Unlike various other special Kapteyn series, the function T (ϵ) does not seem to possess a closed-form...
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  421. Weak and strong type inequalities for Orlicz spaces

    Weak and strong type inequalities for Orlicz spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Louis Labuschagne --- , South Africa
    We revisit the generalisation of Calderon’s Transfer Principle as espoused in [7]. This principle is used to generate weak type maximal inequalities for ergodic operators in the setting of σ-compact locally compact Hausdorff groups acting measure-preservingly on σ-finite measure spaces...
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  422. A rigid Riesz space

    A rigid Riesz space

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A.W. Wickstead --- Queen&rsquo;s University Belfast, , Northern Ireland, UK
    We give an example of an Archimedean Riesz space on which every automorphism is a strictly positive multiple of the identity.
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  423. New congruences modulo 9 for the coefficients of Gordon-McIntosh&#039;s mock theta function &lt;em&gt;&xi;&lt;/em&gt;(&lt;em&gt;q&lt;/em&gt;)

    New congruences modulo 9 for the coefficients of Gordon-McIntosh's mock theta function ξ(q)

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Olivia X.M. Yao --- Suzhou University of Science and Technology, China
    In recent years, congruence properties for the coefficients of mock theta functions have been studied by mathematicians. Recently, Silva and Sellers proved some congruences modulo 3 and 9 for the coefficients of the third order mock theta function ξ(q) given...
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  424. On the existence of block-transitive Steiner designs with &lt;em&gt;k&lt;/em&gt; divides &lt;em&gt;v&lt;/em&gt;

    On the existence of block-transitive Steiner designs with k divides v

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Zheng Huang --- Hunan University of Science and Technology, P.R. China Weijun Liu --- Central South University, P.R. China Lihua Feng --- Central South University, P.R. China
    In this paper, we prove that there is no block-transitive 4-(v, k, 1) designs and 6-(v, k, 1) designs with k divides v.
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  425. Lie derivable maps at unit operator on nest algebras

    Lie derivable maps at unit operator on nest algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Kaipeng Li --- Xidian University, P.R. China Lei Liu --- Xidian University, P.R. China
    Let be a nontrivial nest on a separable Hilbert space and be the associated nest algebra. In this note, we prove that, if contains an atom of infinite rank or is uncountable, then the unit operator I is a Lie...
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  426. On property-(&lt;em&gt;R&lt;/em&gt; &lt;sub&gt;1&lt;/sub&gt;) and relative Chebyshev centers in Banach spaces-II

    On property-(R 1) and relative Chebyshev centers in Banach spaces-II

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Syamantak Das --- Indian Institute of Technology Hyderabad, India Tanmoy Paul --- Indian Institute of Technology Hyderabad, India
    We continue to study (strong) property-(R 1) in Banach spaces. As discussed by Pai & Nowroji in [On restricted centers of sets, J. Approx. Theory, 66(2), 170–189 (1991)], this study corresponds to a triplet , where X is a Banach...
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  427. On the injectivity with respect to &lt;em&gt;q&lt;/em&gt; of the Lupaş &lt;em&gt;q&lt;/em&gt;-transform

    On the injectivity with respect to q of the Lupaş q-transform

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: &Ouml;vg&uuml; G&uuml;rel Yılmaz --- Recep Tayyip Erdogan University, Turkey Sofiya Ostrovska --- Atilim University, Turkey Mehmet Turan --- Atilim University, Turkey
    The Lupaş q-transform has first appeared in the study of the Lupaş q-analogue of the Bernstein operator. Given 0 < q < 1 and f ∈ C [0, 1], the Lupaş q-transform is defined by
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  428. Group properties and similarity transformations for generalized peakon equation with cubic nonlinearities

    Group properties and similarity transformations for generalized peakon equation with cubic nonlinearities

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: P.G.L Leach --- Institute of Systems Science, Durban University of Technology, Republic of South Africa Andronikos Paliathanasis --- Institute of Systems Science, Durban University of Technology, South Africa
    We perform a detailed analysis of the point transformations which leave invariant the Geng-Xue equation. We find that the Geng-Xue equation admits six Lie point symmetries which possess two three-dimensional subalgebras, the A 2,1 ⊗s A 1 and A 3,8...
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  429. Fixed points of principal &lt;em&gt;E&lt;/em&gt; &lt;sub&gt;6&lt;/sub&gt;-bundles over a compact algebraic curve

    Fixed points of principal E 6-bundles over a compact algebraic curve

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: &Aacute;lvaro Ant&oacute;n-Sancho --- Fray Luis de Leon University College of Education, Catholic University of &Aacute;vila, Spain
    Let X be a compact algebraic curve of genus g ≥ 2. The nontrivial outer automorphism σ of the complex Lie group E 6 acts on the moduli space M(E 6) of principal E 6-bundles over X , and this...
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  430. Concircularly semi-symmetric metric connection

    Concircularly semi-symmetric metric connection

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Miroslav D. Maksimović --- University of Pri&scaron;tina in Kosovska Mitrovica, Serbia Milo&scaron; Z. Petrović --- University of Ni&scaron;, Serbia Nenad O. Vesić --- Mathematical Institute of Serbian Academy of Sciences and Arts, University of Belgrade, Milan Lj. Zlatanović --- University of Ni&scaron;, Serbia
    Results on a concircularly semi-symmetric metric connection on a Riemannian manifold are presented. Six linearly independent curvature tensors with respect to this non-symmetric linear connection are studied, and the tensors coincident with the Weyl projective curvature tensor and the concircular...
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  431. On the product of vanishing classes in a finite group

    On the product of vanishing classes in a finite group

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Neda Ahanjideh --- Shahrekord University, Iran
    Let G be a finite group. An element g ∈ G is called a vanishing element of G if there exists an irreducible complex character χ of G such that χ(g) = 0. The conjugacy class of G containing a...
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  432. Two classes of operators related to positively limited sets on Banach lattices

    Two classes of operators related to positively limited sets on Banach lattices

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Halimeh Ardakani --- Payame Noor University, Iran Jin Xi Chen --- Southwest Jiaotong University, China
    This paper is devoted to two classes of operators related to positively limited sets on Banach lattices, which we call positively limited operators and positively limited completely continuous operators, respectively. We study the relationship between these two classes of operators...
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  433. Double total domination in the generalized lexicographic product of graphs

    Double total domination in the generalized lexicographic product of graphs

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Abel Cabrera-Mart&iacute;nez --- Universidad de C&oacute;rdoba, Spain Ismael R&iacute;os Villamar --- Universidad Aut&oacute;noma de Guerrero, Mexico Juan M. Rueda-V&aacute;zquez --- Universidad de C&oacute;rdoba, Spain Jos&eacute; M. Sigarreta Almira --- Universidad Aut&oacute;noma de Guerrero, Mexico
    Let G be a graph of minimum degree at least two. A set D ⊆ V(G) is said to be a double total dominating set of G if |N (v) ∩ D| ≥ 2 for every vertex v ∈ V(G)...
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  434. Idempotents in Banach Algebras II

    Idempotents in Banach Algebras II

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Rudi Brits --- University of Johannesburg, South Africa Muhammad Hassen --- University of Johannesburg, South Africa Francois Schulz --- University of Johannesburg, South Africa
    Let A be a complex and unital Banach algebra, and let E denote the collection of idempotents of A. An old paper of J. Zemánek’s, which was really the starting point of studies of idempotents in general Banach algebras, exhibits...
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  435. Periodic solution for perturbed Hamiltonian systems

    Periodic solution for perturbed Hamiltonian systems

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Khaled Khachnaoui --- University of Kairouan, Tunisia
    In this paper, we study the existence of infinitely many periodic solutions for second-order perturbed Hamiltonian systems. By using variational methods, we obtain new criteria to guarantee the existence of infinitely many periodic solutions using Bolle’s perturbation method. Our results...
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  436. General decay and blow up of solutions for a plate viscoelastic &lt;em&gt;p&lt;/em&gt;(&lt;em&gt;x&lt;/em&gt;)-Kirchhoff type equation with variable exponent nonlinearities and boundary feedback

    General decay and blow up of solutions for a plate viscoelastic p(x)-Kirchhoff type equation with variable exponent nonlinearities and boundary feedback

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jorge Ferreira --- Federal Fluminense University, Brazil Erhan Pişkin --- Dicle University, Turkey Mohammad Shahrouzi --- Jahrom University, Iran
    In this paper, we consider a plate viscoelastic p(x)–Kirchhoff type equation with variable-exponent nonlinearities of the form
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  437. On slant Riemannian submersions from conformal Sasakian manifolds

    On slant Riemannian submersions from conformal Sasakian manifolds

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mehraj Ahmad Lone --- National Institute of Technology Srinagar, India Towseef Ali Wani --- National Institute of Technology Srinagar, India
    In this paper, we study slant Riemannian submersions from conformal Sasakian manifolds onto Riemannian manifolds. We investigate the geometry of foliations associated with the submersion and give sufficient conditions for the submersion to be harmonic.
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  438. The number of distinguishing colorings of a Cartesian product graph

    The number of distinguishing colorings of a Cartesian product graph

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Saeid Alikhani --- Yazd University, Iran Mohammad H. Shekarriz --- Yazd University, Iran
    A vertex coloring is called distinguishing if the identity is the only automorphism that can preserve it. The distinguishing threshold θ(G) of a graph G is the minimum number of colors k required that any arbitrary k-coloring of G is...
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  439. On the characteristic functions and Dirchlet-integrable solutions of singular left-definite Hamiltonian systems

    On the characteristic functions and Dirchlet-integrable solutions of singular left-definite Hamiltonian systems

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Elgiz Bairamov --- Ankara University, Turkey Kenan Tas --- Usak University, Turkey Ekin Uğurlu --- &Ccedil;ankaya University, Turkey
    In this work, a singular left-definite Hamiltonian system is considered and the characteristic-matrix theory for this Hamiltonian system is constructed. Using the results of this theory we introduce a lower bound for the number of Dirichlet-integrable solutions. Moreover we share...
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  440. Near universal property of a quadratic form of Hessian discriminant 4

    Near universal property of a quadratic form of Hessian discriminant 4

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jesse Ira Deutsch --- , Botswana
    A quadratic form is universal if it represents all totally positive integers in a number field. In classical number theory over the rational integers there are some results where a quadratic form takes on all positive integer values except for...
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  441. Argument estimates associated with meromorphic close-to-starlike and Bazilević functions

    Argument estimates associated with meromorphic close-to-starlike and Bazilević functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Nak Eun Cho --- Pukyong National University, Republic of Korea Inhwa Kim --- Harris-Stowe State University, U.S.A H.M. Srivastava --- University of Victoria, Canada
    The object of the present paper is to derive some argument properties associated with meromorphic close-to-starlike and Bazilević functions in the punctured open unit disk. Furthermore, we investigate integral-preserving properties in a sector with some special cases of the main...
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  442. Discrete selectivity, shrinking properties, and disjoint local &lt;em&gt;&pi;&lt;/em&gt;-bases

    Discrete selectivity, shrinking properties, and disjoint local π-bases

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Gary Gruenhage --- Auburn University, U.S.A Vladimir V. Tkachuk --- Universidad Aut&oacute;noma Metropolitana, Mexico
    Using binary function spaces, we give an example of a pseudocompact discretely selective topological group. We show that, under PFA, every compact space of countable tightness has a countable disjoint local π-base at every point. If X is a compact...
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  443. Generating functions of multiple &lt;em&gt;t&lt;/em&gt;-star values

    Generating functions of multiple t-star values

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Zhonghua Li --- Tongji University, China Lu Yan --- Tongji University, China
    In this paper, we study the generating functions of multiple t-star values with an arbitrary number of blocks of twos, which are based on the results of the corresponding generating functions of multiple t-harmonic star sums. These generating functions can...
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  444. Oscillation results for nonlinear weakly canonical fourth-order delay differential equations via canonical transform

    Oscillation results for nonlinear weakly canonical fourth-order delay differential equations via canonical transform

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Natarajan Prabaharan --- Engineering College, Kavaraipettai, India Ethiraju Thandapani --- University of Madras, India Ercan Tun&ccedil; --- Tokat Gaziosmanpaşa University, Turkey
    By using canonical transformation technique, we convert the nonlinear weakly canonical fourth-order delay differential equations into strongly canonical equations. Then we apply oscillation results for canonical equations to get similar results for the studied equation. The significance and novelty of...
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  445. Orbit spaces of free involutions on the product of three spheres

    Orbit spaces of free involutions on the product of three spheres

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Dimpi --- University of Delhi, India Hemant Kumar Singh --- University of Delhi, India
    In this paper, we have determined the orbit spaces of free involutions on a finitistic space having mod 2 cohomology of the product of three spheres . This paper generalizes the results proved by Dotzel et al. [7] for free...
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  446. Lattice characterization of extreme positive operators

    Lattice characterization of extreme positive operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jamel Jaber --- Tunis-El Manar University, Tunis Adnen Khalfaoui --- Tunis-El Manar University, Tunis
    We present a lattice-based characterization of extreme points whithin well-defined convex subsets of positive operators, operating between Banach lattices with quasi-interior points.
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  447. On uniquely packable trees

    On uniquely packable trees

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Alochukwu --- Albany State University, USA M. Dorfling --- University of Johannesburg, South Africa E. Jonck --- University of the Witwatersrand, South Africa
    An i-packing in a graph G is a set of vertices that are pairwise at distance more than i. A packing colouring of G is a partition X = {X 1, X 2, . . . , X k...
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  448. A comonadicity theorem for partial comodules

    A comonadicity theorem for partial comodules

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Eliezer Batista --- Universidade Federal de Santa Catarina, Brazil William Hautekiet --- Universit&eacute; Libre de Bruxelles, Belgium Joost Vercruysse --- Universit&eacute; Libre de Bruxelles, Belgium
    We show that the category of partial comodules over a Hopf algebra H is comonadic over Vectk and provide an explicit construction of this comonad using topological vector spaces. The case when H is finite-dimensional is treated in detail. A...
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  449. The second nonlinear mixed bi-skew Lie triple derivations on factor von Neumann algebras

    The second nonlinear mixed bi-skew Lie triple derivations on factor von Neumann algebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Yuan Yang --- Shaanxi Normal University, People&rsquo;s Republic of China Jianhua Zhang --- Shaanxi Normal University, People&rsquo;s Republic of China
    Let be a factor von Neumann algebra with dim . In this paper, it is shown that if a map satisfies for all , then ϕ is an additive ∗-derivation, where .
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  450. Almost Yamabe solitons satisfying certain conditions on the associated vector field

    Almost Yamabe solitons satisfying certain conditions on the associated vector field

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Rahul Poddar --- Sri Sathya Sai Institute of Higher Learning, India Ramesh Sharma --- University of New Haven, USA S. Balasubramanian --- Sri Sathya Sai Institute of Higher Learning, India
    We study an almost Yamabe soliton (Mn , g, V, ρ) and obtain various conditions on V in terms of infinitesimal harmonic transformation, 2-Killing, and an inequality, to show that V is Killing. In addition, we have provided characterizations of...
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  451. Words over a finite alphabet avoiding 1243

    Words over a finite alphabet avoiding 1243

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Toufik Mansour --- University of Haifa, Israel
    In this paper, we establish a system of recurrence relations and an algorithm for finding the generating function Ak (x) for the number of words over alphabet [k] of length n that avoid 1243, for arbitrary k. In particular, we...
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  452. On conjugacy of additive actions in the affine Cremona group

    On conjugacy of additive actions in the affine Cremona group

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ivan Arzhantsev --- HSE University, Russia
    An additive action on an irreducible algebraic variety X is an effective action with an open orbit of the vector group . Any two additive actions on X are conjugate by a birational automorphism of X. We prove that, if...
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  453. A lemma on &lt;em&gt;C&lt;/em&gt; &lt;sub&gt;0&lt;/sub&gt;-semigroups on time scales and approximate controllability of the heat dynamic equation

    A lemma on C 0-semigroups on time scales and approximate controllability of the heat dynamic equation

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Martin Bohner --- Missouri University of Science and Technology, USA Cosme Duque --- Universidad de Los Andes, Hugo Leiva --- University YachayTech, School of Mathematical and Computational Sciences, Ecuador Zoraida Sivoli --- Universidad Siglo 21,
    In this paper, we present a lemma that allows us to characterize a broad class of C 0-semigroups on time scales, which can be applied to prove existence and uniqueness of solutions of systems of partial differential equations where the...
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  454. A generalization of Riesz* homomorphisms on order unit spaces

    A generalization of Riesz* homomorphisms on order unit spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Florian Boisen --- Institut f&uuml;r Analysis, TU Dresden, Germany Valentin G. H&ouml;lker --- Institut f&uuml;r Analysis, TU Dresden, Germany Anke Kalauch --- Institut f&uuml;r Analysis, TU Dresden, Germany Janko Stennder --- Institut f&uuml;r Analysis, TU Dresden, Germany Onno van Gaans --- Leiden University, The Netherlands
    Riesz homomorphisms on vector lattices have been generalized to Riesz* homomorphisms on ordered vector spaces by van Haandel using a condition on sets of finitely many elements. Van Haandel attempted to prove that it suffices to take sets of two...
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  455. On mid (&lt;em&gt;p&lt;/em&gt;, &lt;em&gt;r&lt;/em&gt;)-compact operators

    On mid (p, r)-compact operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Salthiel Malesela Maepa --- University of Pretoria, South Africa Brian Chihinga Ndumba --- University of Pretoria, South Africa
    Let 1 ≤ p ≤ ∞ and 1 ≤ r ≤ p* where p* is the conjugate index of p. We introduce and study mid (p, r)-compact sets and operators. We begin by introducing and defining the mid (p, r)-compact...
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  456. On the skew eigenvalues of joined union of oriented graphs and applications

    On the skew eigenvalues of joined union of oriented graphs and applications

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Hilal A. Ganie --- , India Archana Ingole --- , India Ujwala Deshmukh --- , India
    Let be an oriented graph with n vertices and m arcs having underlying graph G. The skew matrix of oriented graph , denoted by is a (−1, 0, 1)- skew symmetric matrix. The skew eigenvalues of are the eigenvalues of...
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  457. Notes on sublocales and dissolution

    Notes on sublocales and dissolution

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jorge Picado --- University of Coimbra, Portugal Ale&scaron; Pultr --- Charles University, Czech Republic
    The dissolution (introduced by Isbell in [3], discussed by Johnstone in [5] and later exploited by Plewe in [12, 13]) is here viewed as the relation of the geometry of L with that of the more dispersed T(L) = S(L)op...
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  458. Some measure-theoretic aspects of fractal functions: invariant measures and function spaces

    Some measure-theoretic aspects of fractal functions: invariant measures and function spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Megha Pandey --- , India Tanmoy Som --- , India Saurabh Verma --- , India
    Barnsley (1986) introduced the concept of fractal interpolation functions (FIFs). Thereafter, numerous theories have been developed concerning FIFs and their properties. In this article, we explore some measure theoretic aspects of FIFs generated by the method given by Barnsley. We...
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  459. Conformally flat almost cosymplectic 3-manifolds

    Conformally flat almost cosymplectic 3-manifolds

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Wenjie Wang --- Zhengzhou University of Aeronautics, P.R. China
    In this paper, we consider an almost cosymplectic 3-manifold M such that its scalar curvature is invariant along the Reeb vector field. We prove that if the Reeb vector field of M is harmonic, then M is conformally flat if...
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  460. Atomicity of positive monoids

    Atomicity of positive monoids

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Scott T. Chapman --- Sam Houston State University, Marly Gotti --- Data Science &amp; Engineering,
    An additive submonoid of the nonnegative cone of the real line is called a positive monoid. Positive monoids consisting of rational numbers (also known as Puiseux monoids) have been the subject of several recent papers. Moreover, those generated by a...
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  461. On (&lt;em&gt;k&lt;/em&gt;, &lt;em&gt;ℓ&lt;/em&gt;)-locating colorings of graphs

    On (k, ℓ)-locating colorings of graphs

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Michael A. Henning --- University of Johannesburg, South Africa Mostafa Tavakoli --- Ferdowsi University of Mashhad, Iran
    Let c: V(G) → {1, . . . , ℓ} = [ℓ] be a proper vertex coloring of G and C(i) = {u ∈ V(G): c(u) = i} for i ∈ [ℓ]. The k-color code rk (v|c) of vertex v...
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  462. On positive solutions of the Cauchy problem for doubly nonlocal equations

    On positive solutions of the Cauchy problem for doubly nonlocal equations

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sanping Rao --- Nanchang Institute of Technology, P.R. China Chunxiao Yang --- Xi&rsquo;an University of Architecture and Technology, P.R. China Jinge Yang --- Nanchang Institute of Technology, P.R. China
    We study the Cauchy problem for the doubly nonlocal equation
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  463. Norm and relative uniform convergence

    Norm and relative uniform convergence

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Zili Chen --- Southwest Jiaotong University, China Fu Zhang --- Southwest Jiaotong University, China
    In this paper, we show that if H is a Dedekind complete normed Riesz space with the local Egoroff property, then H is lattice isomorphic to an ideal of an AM-space if and only if for any order bounded norm...
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  464. Some results on anti-pre-Lie superalgebras and admissible Novikov superalgebras

    Some results on anti-pre-Lie superalgebras and admissible Novikov superalgebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Zhao Chen --- Guangxi University for Nationalities, China Shanshan Liu --- Shenzhen Technology University, China Liangyun Chen --- Northeast Normal University, China
    In this paper, we extend the notion of anti-pre-Lie algebras to the ℤ2-graded version, and introduce the notion of anti-pre-Lie superalgebras. They can be characterized as a class of Lie-admissible superalgebras that satisfy its negative left multiplication operators are the...
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  465. Sophie Germain prime &lt;em&gt;p&lt;/em&gt; and the permutation of product of first &lt;em&gt;p&lt;/em&gt; cycles

    Sophie Germain prime p and the permutation of product of first p cycles

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M. Makeshwari --- Central University of Tamil Nadu, India V.P. Ramesh --- Central University of Tamil Nadu, India R. Thangadurai --- Harish-Chandra Research Institute, A CI of Homi Bhabha National Institute, India
    For a natural number n, the permutation (n!) is defined as the left-to-right product of the first n cycles, namely, . In this article, we prove that for any natural number n, 2 is a primitive root of 2n +...
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  466. On variants and generalizations of &lt;em&gt;J&lt;/em&gt;-frames

    On variants and generalizations of J-frames

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Siyabonga S. Dubazana --- University of KwaZulu-Natal, S.A. Simo S. Mthethwa --- University of KwaZulu-Natal, S.A.
    A J-frame is a pointfree topology counterpart of the concept of a J-space. In this paper, we present a study of some frames satisfying conditions that are stronger (and some that are weaker) than those defining J-frames. Conditions under which...
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  467. Well-posedness result for the flow of Maxwell viscoelastic fluid of White-Metzner type

    Well-posedness result for the flow of Maxwell viscoelastic fluid of White-Metzner type

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Djohra Dekhil --- University of Science and Technology Houari Boumdiene USTHB, Algeria Toufik Laadj --- University of Science and Technology Houari Boumdiene USTHB, Algeria Khaled M&rsquo;hamed-messaoud --- University of Science and Technology Houari Boumdiene USTHB, Algeria
    In this paper, we investigate the flow characteristics of an unsteady quasistatic Maxwell viscoelastic fluid of White-Metzner type within a three-dimensional bounded domain. Our objective is to establish the well-posedness of the resulting partial differential equations initial boundary value problem,...
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  468. The maximum norm error estimate and Richardson extrapolation methods of a second-order box scheme for a hyperbolic-difference equation with shifts

    The maximum norm error estimate and Richardson extrapolation methods of a second-order box scheme for a hyperbolic-difference equation with shifts

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Dingwen Deng --- Nanchang Hangkong University, China Zhu-an Wang --- Nanchang Hangkong University, China Zilin Zhao --- Nanchang Hangkong University, China
    The study aims at the development and theoretical analyses of a box method used to solve a kind of hyperbolic equations with shifts. By using the discrete energy method, it is shown that numerical solutions converge to exact solutions with...
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  469. Validity and reliability of the Compassion Fatigue Short Scale among nursing interns

    Validity and reliability of the Compassion Fatigue Short Scale among nursing interns

    Item type: Journal Article • Journal: Journal of Psychology in Africa • Authors: Li-Juan Yi --- Hunan Traditional Chinese Medical College, China Ting Shuai --- Peking University School and Hospital of Stomatology &amp; National Clinical Research Center for Oral Diseases &amp; National Engineering Laboratory for Digital and Material Technology of Stomatology &amp; Beijing Key Laboratory of Digital Stomatology, China Ya Li --- Hunan Traditional Chinese Medical College, China Guo-Hao Wang --- Tangshan Polytechnic University, China Hai-Yan Long --- Hunan Traditional Chinese Medical College, China Hang Lin --- Hunan Traditional Chinese Medical College, China Xu Tian --- Chongqing Traditional Chinese Medicine Hospital, China Maria F. Jim&eacute;nez-Herrera --- Universitat Rovira i Virgili, Spain
    We aimed to determine the reliability and validity of scores from the Chinese Compassion Fatigue Short Scale (CFSS) for nursing interns (n = 229; female = 88.2%, mean age = 20.34 years, SD = 0.968 years). The nursing interns completed...
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  470. A survey and exposition of sub-Hausdorff separation axioms

    A survey and exposition of sub-Hausdorff separation axioms

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jeffrey T. Denniston --- Kent State University, USA Austin Melton --- Kent State University, USA Stephen E. Rodabaugh --- Institute for Applied Topology and Topological Structures, Youngstown State University, USA Jamal K. Tartir --- Institute for Applied Topology and Topological Structures, Youngstown State University, USA
    This paper surveys and develops sub-Hausdorff axioms. It augments known relationships involving T 0 (Kolmogorov), S 0 (quasi-sobriety), S 1 (sobriety), T 1 (Fréchet), and T 2 (Hausdorff ) by examining a large suite of sub-Hausdorff axioms. Emphasis is given...
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  471. Nontrivial solutions for multiparameter &lt;em&gt;k&lt;/em&gt;-Hessian systems

    Nontrivial solutions for multiparameter k-Hessian systems

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Huanhuan Ding --- Northwest Normal University, People&rsquo;s Republic of China Chenghua Gao --- Northwest Normal University, People&rsquo;s Republic of China Xingyue He --- Northwest Normal University, People&rsquo;s Republic of China
    This paper is devoted to studying the coupled system of multiparameter k-Hessian equations
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  472. On a class of third-order dissipative differential operator with distributional potentials

    On a class of third-order dissipative differential operator with distributional potentials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ji-jun Ao --- Inner Mongolia University of Technology, China Fei-fan Li --- Inner Mongolia University of Technology, China
    This paper aims to investigate a class of boundary value problems generated by a third-order differential equation with distributional potentials and some dissipative boundary conditions. We first construct an operator related to the problem, then prove that the operator is...
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  473. On graded-nonnil-Noetherian commutative rings

    On graded-nonnil-Noetherian commutative rings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Anass Assarrar --- University S.M. Ben Abdellah Fez, Morocco Najib Mahdou --- University S.M. Ben Abdellah Fez, Morocco
    Our present work is motivated by several papers which have introduced and studied the notion of nonnil-Noetherian rings. Let A = ⊕ α ∈G A α be a commutative ring with unity graded by an arbitrary commutative monoid G...
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  474. On &lt;em&gt;z&lt;/em&gt;-ideals and &lt;em&gt;z&lt;/em&gt;-closure operations of semirings, I

    On z-ideals and z-closure operations of semirings, I

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Amartya Goswami --- University of Johannesburg, South Africa
    The aim of this series of papers is to study z-ideals of semirings. In this article, we introduce some distinguished classes of z-ideals of semirings, which include z-prime, z-semiprime, z-irreducible, and z-strongly irreducible ideals and study some of their properties...
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  475. A note on the U-Dunford-Pettis operators

    A note on the U-Dunford-Pettis operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Farid Afkir --- Moulay Ismail University of Meknes, Morocco Aziz Elbour --- Moulay Ismail University of Meknes, Morocco
    The purpose of this note is to give a correct proof of the theorem that concerns the domination property of the class of U-Dunford-Pettis operators obtained by O. Aboutafail, K. El Fahri, J. H’Michane and L. Zraoula [On the class...
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  476. Best approximation theorems via relatively &lt;em&gt;u&lt;/em&gt;-continuous and Jaggi nonexpansive mappings

    Best approximation theorems via relatively u-continuous and Jaggi nonexpansive mappings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M. Gabeleh --- Ayatollah Boroujerdi University, Iran R. Gholipour --- Yazd University, Iran H. Mazaheri --- Yazd University, Iran S.P. Moshokoa --- Tshwane University of Technology, South Africa
    In this paper, we introduced a new type of cyclic (noncyclic) mappings, called Jaggi relatively nonexpansive mappings and use to investigate the existence of best proximity points (pairs) in the framework of reflexive (strictly convex) Banach spaces by using a...
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  477. Parallel sum

    Parallel sum

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Stefan Stankov --- University of Ni&scaron;, Serbia
    In this paper, we will consider parallel summable operators on Hilbert space. Operators A and B are said to be parallel summable if and . We will prove that the parallel sum can be represented as A: B = A(A...
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  478. Lattice points on polyominoes of inversion sequences

    Lattice points on polyominoes of inversion sequences

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jos&eacute; L. Herrera --- Universidad del Cauca, Colombia Toufik Mansour --- University of Haifa, Israel J.L. Ram&iacute;rez --- Universidad Nacional de Colombia, Colombia
    Inversion sequences of length n are positive integer sequences e 1 e 2 …e n such that 1 ≤ ei ≤ i for all 1 ≤ i ≤ n. These sequences are in bijection with the permutations of [n]...
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  479. A note on fibers and Vietoris topologies of paratopological groups

    A note on fibers and Vietoris topologies of paratopological groups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Yu-Ming Deng --- Beijing University of Technology, China Liang-Xue Peng --- Beijing University of Technology, China
    If f: G → Y is an irreducible closed continuous mapping defined on a regular weakly collectionwise normal first-countable meta-Lindelöf locally σ paratopological group G onto a T 1-space Y which has a neighborhood ωω -base at a point y...
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  480. The grazer &lt;em&gt;Cymbula oculus&lt;/em&gt; (Patellogastropoda: Patellidae) serves as an important settlement substrate for several of its macroalgal prey

    The grazer Cymbula oculus (Patellogastropoda: Patellidae) serves as an important settlement substrate for several of its macroalgal prey

    Item type: Journal Article • Journal: African Journal of Marine Science • Authors: W Moosa --- University of the Western Cape, South Africa J Phillips --- University of the Western Cape, South Africa GW Maneveldt --- University of the Western Cape, South Africa
    Intertidal communities are predictably affected by both physical and biological factors, with herbivory as a particularly important factor. Instead of dense beds of macroalgae, which typically characterise the mid-eulittoral zone along the south coast of South Africa, at Kalk Bay...
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  481. On a weak law of large numbers and &lt;em&gt;L&lt;sup&gt;p&lt;/sup&gt; &lt;/em&gt;-convergence for general random variables

    On a weak law of large numbers and Lp -convergence for general random variables

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Qi Gao --- Henan Normal University, China Yu Miao --- Henan Normal University, China
    In the present paper, we consider a sequence of the general random variables, which include the sequences of martingale differences, and establish the weak law of large numbers and the convergence in Lp under some weaker conditions.
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  482. Proofs of three conjectured internal congruences modulo 32 for Schur-type overpartitions

    Proofs of three conjectured internal congruences modulo 32 for Schur-type overpartitions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Weifeng Gao --- School of Mathematical Sciences, Suzhou University of Science and Technology, P.R. China Olivia X.M. Yao --- School of Mathematical Sciences, Suzhou University of Science and Technology, P.R. China
    Let S(n) denote the number of overpartitions of Schur-type. Recently, Chern, da Silva and Sellers proved many congruences modulo 8 and 16 for S(n). At the end of their paper, they also posed a conjecture on internal congruences modulo 32...
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  483. Interior vertices and edges in integer partitions

    Interior vertices and edges in integer partitions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Aubrey Blecher --- University of the Witwatersrand, South Africa Charlotte Brennan --- University of the Witwatersrand, South Africa Arnold Knopfmacher --- University of the Witwatersrand, South Africa Toufik Mansour --- University of Haifa, Israel
    This paper characterises the shape of the Young diagram associated with integer partitions in terms of two newly invented statistics which are defined in the text: namely interior vertices and horizontal edges. Generating functions and associated asymptotic results are developed...
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  484. On elliptic curves assigned to a pair of right triangles with an equal hypotenuse

    On elliptic curves assigned to a pair of right triangles with an equal hypotenuse

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Arman Shamsi Zargar --- University of Mohaghegh Ardabili, Iran Seiji Tomita --- Tokyo Software Company (Inc.), Japan
    Consider a pair of right triangles with an equal hypotenuse. This turns out to solve the diophantine system of equations a 2 + b 2 = c 2 + d 2 = e 2 in integers. To this system we...
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  485. Maker-Breaker domination game played on corona products of graphs

    Maker-Breaker domination game played on corona products of graphs

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Athira Divakaran --- Mar Athanasius College, India Tijo James --- Pavanatma College, India Sandi Klavžar --- University of Ljubljana, Slovenia Latha S. Nair --- Mar Athanasius College, India
    In the Maker-Breaker domination game, Dominator and Staller play on a graph G by taking turns in which each player selects a not yet played vertex of G. Dominator’s goal is to select all the vertices in a dominating set,...
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  486. Multiplication operators on the weighted Sobolev disk algebra

    Multiplication operators on the weighted Sobolev disk algebra

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Yucheng Li --- Hebei Normal University, China Kaikai Han --- Hebei University of Economics and Business, China Hexin Zhang --- Hebei Normal University, China
    Let ⅅ be the unit disk in the complex plane ℂ. For α > −1, the weighted Sobolev disk algebra SA(ⅅ, dAα ) consists of all analytic functions in the weighted Sobolev space W 2,2(ⅅ, dAα ). In this paper,...
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  487. Lipschitz closed injective hull ideals and Lipschitz interpolative ideals

    Lipschitz closed injective hull ideals and Lipschitz interpolative ideals

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Rachid Yahi --- University of M&rsquo;sila, University Pole, Algeria Dahmane Achour --- University of M&rsquo;sila, University Pole, Algeria Elhadj Dahia --- University of M&rsquo;sila, University Pole, Algeria
    In this paper we present two constructions: the Lipschitz closed injective hull ideals and the Lipschitz interpolative ideals of a Lipschitz operator ideal. These procedures aim to construct new Lipschitz operator ideals between pointed metric spaces and Banach spaces. The...
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  488. The extended Frobenius problem for Lucas series incremented by a Lucas number

    The extended Frobenius problem for Lucas series incremented by a Lucas number

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Aureliano M. Robles-P&eacute;rez --- Universidad de Granada, Spain Jos&eacute; Carlos Rosales --- Universidad de Granada, Spain
    We study the extended Frobenius problem for sequences of the form {la } ∪ {la + ln } n∈N and {la + ln } n ∈N , where {ln } n∈N is the Lucas series and la is a...
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  489. Quasi-periodic solutions of some impulsive Duffing equations

    Quasi-periodic solutions of some impulsive Duffing equations

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Lu Chen --- Quzhou University, P.R. China
    In the present paper, we study the following Duffing equation
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  490. Multiplicatively maximal numerical range-preserving maps

    Multiplicatively maximal numerical range-preserving maps

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Abdellatif Bourhim --- Syracuse University, USA Mohamed Mabrouk --- Umm Al-Qura University, Saudi Arabia
    Let be the algebra of all bounded linear operators on a complex Hilbert space . For any operator , let W 0(T) be the maximal numerical range of T. We show that two maps φ 1 and φ 2 from...
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  491. On set-star-C-Menger spaces

    On set-star-C-Menger spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Sumit Singh --- Ramjas College, University of Delhi, University Enclave, India
    Motivated by the Arhangel’skii [2] “s-Lindelöf cardinal function” and Kočinac, Konca, and Singh [15] set-star covering properties, we introduce the setstar-C-Menger property. A space X is said to have the set-star-C-Menger property if for each nonempty subset A of X...
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  492. On the analysis and integrability of the time-fractional stochastic potential-KdV equation

    On the analysis and integrability of the time-fractional stochastic potential-KdV equation

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Nida Zinat --- Government College University, Pakistan Akhtar Hussain --- The University of Lahore, Pakistan A.H. Kara --- University of the Witwatersrand, South Africa F.D. Zaman --- Government College University, Pakistan
    This study investigates the invariance properties of the time-fractional stochastic potential-KdV (FSP-KdV) equation, intending to enhance our understanding of the dynamics associated with nonlinear photon and optical soliton propagation. The application of the Lie group analysis method enables the derivation...
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  493. Interpolating inequalities for unitarily invariant norms and numerical radii of matrices

    Interpolating inequalities for unitarily invariant norms and numerical radii of matrices

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ahmad Al-Natoor --- Isra University, Jordan Omar Hirzallah --- The Hashemite University, Jordan Fuad Kittaneh --- The University of Jordan, Jordan
    In this paper, which is a continuation of our works in [9] and [10], we prove several interpolating inequalities for norms and numerical radii of matrices. Special cases of our results present refinements of some known inequalities. Among other results,...
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  494. &lt;em&gt;f&lt;/em&gt;-rough Cauchy sequences

    f-rough Cauchy sequences

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Tamim Aziz --- University of North Bengal, India Sanjoy Ghosal --- University of North Bengal, India
    In this article, we narrated the new notion of rough f-statistical convergence and rough f-statistical Cauchy sequences, successively becoming a more generalized version of rough statistical convergence and rough statistical Cauchy sequences. Consecutively, compare the following important theorems with those...
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  495. Banaschewski compactifications via special rings of functions in the absence of the Axiom of Choice

    Banaschewski compactifications via special rings of functions in the absence of the Axiom of Choice

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Alireza Olfati --- Yasouj University, Iran Eliza Wajch --- University of Siedlce, Poland
    For a topological space is the ring of all continuous real functions f on X such that, for every real number ϵ > 0, there exists a countable clopen cover of X such that the oscillation of f on each...
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  496. On the reduction of powers of self-adjoint operators

    On the reduction of powers of self-adjoint operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Salima Kebli --- University of Oran 1, Algeria Mohammed Hichem Mortad --- University of Oran 1, Algeria
    Let T ∈ B(H) be such that Tn is self-adjoint for some with n ≥ 3. The paper’s primary aim is to establish the conditions that lead to the self-adjointness of T. We pay particular attention to the case where...
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  497. The Common Hermitian Solutions of the matrix equations &lt;inline-formula&gt; &lt;mml:math&gt; &lt;mml:mrow&gt; &lt;mml:msub&gt; &lt;mml:mi&gt;B&lt;/mml:mi&gt; &lt;mml:mn&gt;2&lt;/mml:mn&gt; &lt;/mml:msub&gt; &lt;mml:mi&gt;X&lt;/mml:mi&gt; &lt;mml:msubsup&gt; &lt;mml:mi&gt;B&lt;/mml:mi&gt; &lt;mml:mn&gt;2&lt;/mml:mn&gt; &lt;mml:mo&gt;*&lt;/mml:mo&gt; &lt;/mml:msubsup&gt; &lt;mml:mo&gt;=&lt;/mml:mo&gt; &lt;mml:msub&gt; &lt;mml:mi&gt;A&lt;/mml:mi&gt; &lt;mml:mn&gt;2&lt;/mml:mn&gt; &lt;/mml:msub&gt; &lt;/mml:mrow&gt; &lt;/mml:math&gt; &lt;/inline-formula&gt; and &lt;inline-formula&gt; &lt;mml:math&gt; &lt;mml:mrow&gt; &lt;mml:msub&gt; &lt;mml:mi&gt;B&lt;/mml:mi&gt; &lt;mml:mn&gt;3&lt;/mml:mn&gt; &lt;/mml:msub&gt; &lt;mml:mi&gt;X&lt;/mml:mi&gt; &lt;mml:msubsup&gt; &lt;mml:mi&gt;B&lt;/mml:mi&gt; &lt;mml:mn&gt;3&lt;/mml:mn&gt; &lt;mml:mo&gt;*&lt;/mml:mo&gt; &lt;/mml:msubsup&gt; &lt;mml:mo&gt;=&lt;/mml:mo&gt; &lt;mml:msub&gt; &lt;mml:mi&gt;A&lt;/mml:mi&gt; &lt;mml:mn&gt;3&lt;/mml:mn&gt; &lt;/mml:msub&gt; &lt;/mml:mrow&gt; &lt;/mml:math&gt; &lt;/inline-formula&gt; subject to inequality restrictions

    The Common Hermitian Solutions of the matrix equations B 2 X B 2 * = A 2 and B 3 X B 3 * = A 3 subject to inequality restrictions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Zhanshan Wang --- Northeastern University, P.R. China Huiting Zhang --- Northeastern University, P.R. China Honglin Zou --- Zhejiang Shuren University, P.R. China
    Problem CHS: Given , find such that X ≥ 0 (> 0), where is given by
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  498. Functionally countable subspaces of nice products

    Functionally countable subspaces of nice products

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Vladimir V. Tkachuk --- Universidad Aut&oacute;noma Metropolitana, M&eacute;xico
    We establish that, for any Tychonoff space X of weight ≤ ω 1, if Xδ is the Gδ -modification of X , then Cp (Xδ ) has a dense functionally countable subspace. Furthermore, the space has a dense functionally countable...
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  499. On the preservers of some subsets of the approximate point spectrum

    On the preservers of some subsets of the approximate point spectrum

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: H. Benbouziane --- Faculty of Sciences DharMahraz Fes, University Sidi Mohammed Ben Abdellah, Morocco M. Ech-Ch&eacute;rif El Kettani --- Faculty of Sciences DharMahraz Fes, University Sidi Mohammed Ben Abdellah, Morocco I. El Khchin --- Faculty of Sciences DharMahraz Fes, University Sidi Mohammed Ben Abdellah, Morocco
    Let be an infinite-dimensional complex Banach space and be the algebra of all bounded linear operators on . For , we consider the following spectral sets in approximate point-spectrum, defined by
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  500. On &lt;em&gt;&beta;&lt;/em&gt;-adic expansions of powers of an algebraic integer omitting a digit

    On β-adic expansions of powers of an algebraic integer omitting a digit

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jiuzhou Zhao --- East China Normal University, China Ruofan Li --- Jinan University, China
    Let α, β be two relatively prime algebraic integers in a number field K and N be a positive integer. We show that the number of n ∈ {1, 2, . . . , N} such that the β-adic expansion...
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  501. Diameter of orientations of graphs with given order and number of blocks

    Diameter of orientations of graphs with given order and number of blocks

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: P. Dankelmann --- University of Johannesburg, South Africa M.J. Morgan --- School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, South Africa E.J. Rivett-Carnac --- University of Johannesburg, South Africa
    A strong orientation of a graph G is an assignment of a direction to each edge such that G is strongly connected. The oriented diameter of G is the smallest diameter among all strong orientations of G. A block of...
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  502. The general position number under vertex and edge removal

    The general position number under vertex and edge removal

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Pakanun Dokyeesun --- Institute of Mathematics, Physics and Mechanics, Slovenia Sandi Klavžar --- University of Ljubljana, Slovenia Jing Tian --- School of Science, Zhejiang University of Science and Technology, P.R. China
    Let gp(G) be the general position number of a graph G. It is proved that gp(G − x) ≤ 2gp(G) holds for any vertex x of a connected graph G and that if x lies in some gp-set of G,...
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  503. Some classes satisfying the 2-dimensional Jacobian conjecture and a proof of the complex conjecture until degree 104

    Some classes satisfying the 2-dimensional Jacobian conjecture and a proof of the complex conjecture until degree 104

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Thuy Nguyen --- S&atilde;o Paulo State Univesity (UNESP), Brazil
    We construct a non-proper set of two variables polynomial maps and study the nowhere vanishing Jacobian condition of the Jacobian conjecture for this set. We obtain some classes of polynomial maps satisfying the 2-dimensional Jacobian conjecture for both real and...
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  504. New properties of some classes of Saphar type operators

    New properties of some classes of Saphar type operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Ayoub Ghorbel --- University of Sfax, Tunisia Snežana Č. Živković-Zlatanović --- University of Ni&scaron;, Serbia
    This paper explores additional properties of some classes of Saphar type operators, namely left Drazin invertible, essentially left Drazin invertible, right Drazin invertible, and essentially right Drazin invertible operators on Banach spaces, building upon the groundwork laid in [8] and...
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  505. Umbilicity of complete linear Weingarten hypersurfaces immersed in certain Einstein manifolds

    Umbilicity of complete linear Weingarten hypersurfaces immersed in certain Einstein manifolds

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Henrique F. de Lima --- Universidade Federal de Campina Grande, Brazil Lucas S. Rocha --- Universidade Federal de Campina Grande, Brazil Marco Antonio L. Vel&aacute;squez --- Universidade Federal de Campina Grande, Brazil
    In this paper, we present some sets of geometric conditions that ensure the umbilicity of linear Weingarten hypersurfaces immersed in an Einstein manifold satisfying standard curvature constraints which, in particular, are verified by a Riemannian space with constant sectional curvature...
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  506. On the sum of annihilators in nearrings

    On the sum of annihilators in nearrings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Nastaran Naseripour --- Shahrood University of Technology, Iran Ebrahim Hashemi --- Shahrood University of Technology, Iran Mahsa Paykanian --- Shahrood University of Technology, Iran
    A ring is termed a left IN-ring if the right annihilator of the intersection of any two left ideals is equal to the sum of their right annihilators. As a generalization of left IN-ring, a ring is called a right...
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  507. Generalized &lt;em&gt;A&lt;/em&gt;-numerical radius inequalities in semi-Hilbert spaces through the angle between two vectors

    Generalized A-numerical radius inequalities in semi-Hilbert spaces through the angle between two vectors

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mojtaba Bakherad --- University of Sistan and Baluchestan, Iran
    This paper presents several inequalities related to the A-numerical radius in the context of semi-Hilbert space operators. By integrating modern techniques from operator theory and functional analysis, we derive new inequalities for the A-numerical radius that emphasize the unique characteristics...
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  508. Further remarks on &lt;em&gt;z&lt;/em&gt;-ideals of semirings

    Further remarks on z-ideals of semirings

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Amartya Goswami --- University of Johannesburg, South Africa Ahmed Maatallah --- University of Monastir, Faculty of Sciences of Monastir, Research Laboratory on Algebra, Tunisia
    In this note, we revisit certain results from a previous work of the first author concerning z-ideals of semirings. We demonstrate that the assumption of the semiring being a bzi-semiring can be dispensed with. Additionally, we propose a revised definition...
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  509. Tight Toughness Bounds for Fractional (&lt;em&gt;k, n&lt;/em&gt;)-Critical Graphs with Large &lt;em&gt;n&lt;/em&gt;

    Tight Toughness Bounds for Fractional (k, n)-Critical Graphs with Large n

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Wei Gao --- School of Mathematics, Hohai University, China Weifan Wang --- School of Mathematical Sciences, Zhejiang Normal University, China Yaojun Chen --- School of Mathematics, Nanjing University, China
    A graph G is called a fractional (k, n)-critical graph if G − V ′ admits a fractional k-factor for any V ′ ⊆ V (G) with |V′| = n. The main result in this paper states the following facts:...
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  510. Nil Modules and the Envelope of a Submodule

    Nil Modules and the Envelope of a Submodule

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: David Ssevviiri --- Makerere University, Uganda Annet Kyomuhangi --- Busitema University, Uganda
    Let R be a commutative unital ring and N be a submodule of an R-module M. We show that: 1) the semiprime radical is an invariant on submodules generated by the ascending chain of envelopes of a given submodule; 2)...
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  511. On &lt;em&gt;SV&lt;sub&gt;c&lt;/sub&gt; &lt;/em&gt;-Spaces

    On SVc -Spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Amir Veisi --- Yasouj University, Iran Zahra Keshtkar --- Yasouj University, Iran
    We say that a topological space X is an SVc-space if Cc (X) is an SV - ring, that is, is a valuation ring for every prime ideal P of Cc (X). The purpose of this paper is to study...
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  512. Approximate controllability of a parabolic dynamic equation on homogeneous time scales

    Approximate controllability of a parabolic dynamic equation on homogeneous time scales

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Martin Bohner --- Missouri University of Science and Technology, USA Cosme Duque --- Universidad de Los Andes, Hugo Leiva --- University YachayTech, School of Mathematical and Computational Siences, San Miguel de Urcuqui, Ecuador
    This paper aims to explore the approximate controllability of a semilinear system of parabolic dynamic equations on homogeneous time scales. Building on the innovative semigroup theory for time scales introduced in [13], we leverage a pivotal lemma from [5] that...
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  513. Rayleigh quotients of Dillon&rsquo;s functions

    Rayleigh quotients of Dillon’s functions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Aditi Kar Gangopadhyay --- Indian Institute of Technology Roorkee, India Sugata Gangopadhyay --- Indian Institute of Technology Roorkee, India Mansi Goyal --- Indian Institute of Technology Roorkee, India Aleksandr Kutsenko --- Novosibirsk State University, Russia Bimal Mandal --- Indian Institute of Technology Jodhpur, India
    The Walsh-Hadamard spectrum of a bent function uniquely determines a dual function. The duality mapping is the only isometric mapping on the set of bent functions apart from its automorphisms that preserve bentness. The Hamming distance between a bent function...
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  514. A note on the cube polynomials of Fibonacci and Lucas-Run graphs

    A note on the cube polynomials of Fibonacci and Lucas-Run graphs

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jianxin Wei --- School of Mathematics and Statistics Science, Ludong University, P.R. China
    The cube polynomials of the Fibonacci-run graph and Lucas-run graph are determined, and a conjecture on the relation between them is proved. Note that Mollard (2025) [9] has considered deeply this question and obtained many general conclusions. Here we study...
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  515. On the location of ratios of zeros of special trinomials

    On the location of ratios of zeros of special trinomials

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: I. Ndikubwayo --- Makerere University, Uganda A.S. Bamunoba --- Lira University, Uganda
    Given coprime integers k, ℓ with k > ℓ ⩾ 1, and arbitrary complex polynomials A(z) and B(z) such that deg(A(z)B(z)) ⩾ 1, we consider the polynomial sequence {Pn (z)} satisfying the three-term recurrence relation
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  516. Geometric characterizations of some analytic functions related to the generalized Marcum &lt;em&gt;Q&lt;/em&gt;-function

    Geometric characterizations of some analytic functions related to the generalized Marcum Q-function

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Abdulaziz Alenazi --- College of Science, Northern Border University, Saudi Arabia Khaled Mehrez --- Kairouan Preparatory Institute for Engineering Studies, University of Kairouan, Tunisia
    The aim of this paper is to study certain geometric properties, such as convexity of order α (0 ≤ α < 1) and uniform convexity inside the unit disk, for a class of analytic functions related to the generalized Marcum...
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  517. Characterizations of the semi-harmonious and harmonious quasi-projection pairs on Hilbert &lt;em&gt;C&lt;/em&gt; &lt;sup&gt;&lowast;&lt;/sup&gt;-modules

    Characterizations of the semi-harmonious and harmonious quasi-projection pairs on Hilbert C ∗-modules

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Xiaoyi Tian --- Shanghai Normal University, P.R. China Qingxiang Xu --- Shanghai Normal University, P.R. China Chunhong Fu --- Health School Attached to Shanghai University of Medicine &amp; Health Sciences, P.R. China
    For each adjointable idempotent Q on a Hilbert C ∗ -module , a specific projection m(Q) called the matched projection of Q was introduced recently due to the characterization of the minimum value among all the distances from projections to Q...
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  518. Numerical semigroups of coated odd elements

    Numerical semigroups of coated odd elements

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M.B. Branco --- Universidade de &Eacute;vora, J.C. Rosales --- Universidad de Granada, Spain M.A. Traesel --- Instituto Federal de S&atilde;o Paulo, Brazil
    A numerical semigroup S is coated with odd elements (Coe-semigroup), if {x − 1, x + 1} ⊆ S for all odd elements x in S. In this note, we will study this kind of numerical semigroup. In particular, we...
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  519. Pelczyński&rsquo;s property (V) and (&lt;em&gt;V&lt;/em&gt;&lowast;) on tensor products and spaces of compact operators

    Pelczyński’s property (V) and (V∗) on tensor products and spaces of compact operators

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Qingying Bu --- University of Mississippi, University, USA
    Let U be a reflexive Banach space with an unconditional basis and X be any Banach space. We show that if X has Pelczyński’s property (V) then (U,X) has Pelczyński’s property (V). We also show that if X has Pelczyński’s...
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  520. The role of concave functions in the study of interpolative contractions

    The role of concave functions in the study of interpolative contractions

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Marija Cvetković --- University of Ni&scaron;, Serbia
    The interpolative contraction and its numerous generalizations motivated this study on its relation to previously known classes of contractive mappings. We will prove that by using of the concave property of the logarithmic function (or Jensen’s inequality), it is possible...
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  521. Distance domination and linear-vizing constants

    Distance domination and linear-vizing constants

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Paul Horn --- University of Denver, USA Di Qin --- University of Denver, USA
    Generalizing and strengthening a classical result of Vizing, Rautenbach proved a linear relationship between the domination number, the maximum degree, the number of vertices, and the number of edges for graphs with no isolated vertices. The sharpest version of this...
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  522. Further arithmetic properties of Andrews&rsquo; integer partitions with even parts below odd parts

    Further arithmetic properties of Andrews’ integer partitions with even parts below odd parts

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Abhishek Sarma --- Tezpur University, India
    In 2018, Andrews introduced the partition function , which counts the number of partitions of a positive integer n where each even part is less than each odd part. Furthermore, he defined another class of partitions, namely which counts the...
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  523. On 2-nilpotent multiplier of Lie superalgebras

    On 2-nilpotent multiplier of Lie superalgebras

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Rudra Narayan Padhan --- Government Autonomous College Rourkela, India Kishor Chandra Pati --- National Institute of Technology, India
    In this article, we define the c-nilpotent multiplier of a finite dimensional Lie superalgebra. We characterize the structure of 2-nilpotent multiplier of finite dimensional nilpotent Lie superalgebras whose derived subalgebras have dimension at most one. Then we give an upper...
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  524. Binormal block Toeplitz operators with matrix valued circulant symbols

    Binormal block Toeplitz operators with matrix valued circulant symbols

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Nihat G&ouml;khan G&ouml;ğ&uuml;ş --- Sabanci University Istanbul, Turkey Rewayat Khan --- Sabanci University Istanbul, Turkey Eungil Ko --- Ewha Womans University, Korea Ji Eun Lee --- Sejong University, Republic of Korea
    This paper focuses on the binormality of block Toeplitz operators with matrix valued circulant symbols. We also study some Γ-dilations of Toeplitz operators. Moreover, we also analyze the invariant subspace of Toeplitz operators with matrix-valued symbols.
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  525. Composition operators on the weighted &lt;em&gt;BMOA&lt;/em&gt; spaces with closed range

    Composition operators on the weighted BMOA spaces with closed range

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Rikio Yoneda --- Institute of Human and Social Sciences, Kanazawa University, Japan
    We study the composition operator C φ with closed range on the weighted space :
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  526. Cauchy approachable functions and spaces

    Cauchy approachable functions and spaces

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Pratulananda Das --- Department of Mathematics, Jadavpur University, India Sujan Khna --- Department of Mathematics, Jadavpur University, India Sudip Kumar Pal --- Department of Mathematics, Diamond Harbour Women&rsquo;s University, India
    In the context of functions between metric spaces, we introduce a new class of functions which we called Cauchy approachable function which happens to lie between the classes of continuous functions and Cauchy regular functions. A significant characteristic of these...
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  527. A blind signature scheme based on new cyclic groups

    A blind signature scheme based on new cyclic groups

    Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Elahe Mehraban --- Mathematics Research Center, Near East University TRNC, Turkey T. Aaron Gulliver --- Department of Electrical and Computer Engineering, University of Victoria, Canada Evren Hincal --- Mathematics Research Center, Near East University TRNC, Turkey
    In this paper, the Fibonacci, Lehmer, and Mersenne sequences are used to define new sequences named the Hadamard-type Fibonacci-Lehmer sequences and Mersenne-Lehmer sequences, and some results regarding them are given. Then these sequences are employed to introduce new cyclic groups...
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