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Natural Alternatives For One Dimensional Median Filtering
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: C.H. Rohwer M. WildFor practical purposes median smoothers have often been considered the basic components for the construction of simple non-linear smoothers for removing impulsive noise before any subsequent linear signal extraction from a sequence. Alternatives exist that are computationally convenient, conceptually simpler... -
Maximal Ideals in Near-Rings And Semigroups
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: HenryE. Heatherly RalphP. TucciThis paper gives conditions that guarantee that a near-ring or a semi- group has maximal right, left, or two-sided ideals. Stronger results are obtained for those semigroups which are adjoint semigroups of rings. Examples are given which illustrate and delimit... -
On the Unboundedness of Control Operators for Bilinear Systems
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Abdelali IdrissiThe aim of this work is to study the classes of unbounded linear control operators which ensure the existence and uniqueness of the mild and strong solutions of certain bilinear control systems. By an abstract approach, similar to that adopted... -
Spectral Mapping Theorems For Evolution Semigroups on Spaces of Almost Periodic Functions
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Walter Hutter Frank Räbiger. We show that the weak spectral mapping theorem holds for evolution semigroups on spaces of periodic functions. Furthermore, we prove the spectral mapping theorem for evolution semigroups on spaces of (weakly asymptotically) almost periodic functions. The results are applied... -
A Lemma On C 0 -semigroups And Applications
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Hugo LeivaIn this note we characterize a large class of C 0-semigroups which can be applied to prove the existence and the uniqueness of the solutions of many systems of partial differential equations. In fact, we apply our result to a... -
The
Lu Lu -semigroup for Envelopes Of Functions Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: E. Malkowsky C.H. RohwerIn the theory of non-linear smoothers a semigroup of operators has been established, that structures the rank based selectors in a lattice for the purpose of comparison and analysis. The well known upper and lower envelopes of functions can be... -
Stability of asymptotic properties of Hille-yosida operators under perturbations and retarded differential equations
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Lahcen ManiarWe give conditions on the strongly continuous semigroup (T 0(t)) t≥0, generated by the part of a Hille-Yosida operator A on X 0 := D(A), and a non-autonomous family of operators (B(t)) t≥0 such that the evolution family (U(t,s)) t≥s≥0,... -
Semigroups of transformations with fixed sets
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Preeyanuch Honyam --- Department of Mathematics, Faculty of Science, Thailand Jintana Sanwong --- Department of Mathematics, Faculty of Science, ThailandLet T (X) denote the semigroup (under composition) of transformations from X into itself. For a fixed subset Y of X, let Fix(X, Y) be the set of all self-maps on X which fix all elements in Y. Then Fix(X,... -
Montel resolvents and uniformly mean ergodic semigroups of linear operators
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: AngelaA. Albanese --- Dipartimento di Matematica e Fisica “E. De Giorgi”, Italy José Bonet --- Instituto Universitario de Matemática Pura y Aplicada IUMPA, Spain WernerJ. Ricker --- Math.-Geogr. Fakultät, GermanyFor C 0-semigroups of continuous linear operators acting in a Banach space criteria are available which are equivalent to uniform mean ergodicity of the semigroup, meaning the existence of the limit (in the operator norm) of the Cesàro or Abel... -
On character amenability of semigroup algebras
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: S.M. Maepa --- , , South Africa O.T. Mewomo --- , , South AfricaWe 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... -
Eliahou number, Wilf function and concentration of a numerical semigroup
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Patricio Almirón --- Universidad Complutense de Madrid, Spain Julio José Moyano-Fernández --- Departamento de Matemáticas & Institut Universitari de Matemátiques i Aplicacions de Castelló, SpainWe 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... -
The complexity of a numerical semigroup
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: J.I. García-García --- Universidad de Cádiz, Spain M.A. Moreno-Frías --- Universidad de Cádiz, Spain J.C. Rosales --- Universidad de Granada, Spain A. Vigneron-Tenorio --- Universidad de Cádiz, SpainLet S and Δ be numerical semigroups. A numerical semigroup S is an I(Δ)-semigroup if S \ {0} is an ideal of Δ. We denote by S is an I(Δ)-semigroup}, and we say that Δ is an ideal extension... -
Haagerup property of semigroup crossed products
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Qing Meng --- Qufu Normal University, ChinaIn 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... -
Equidivisibility and profinite coproduct
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jorge Almeida --- Universidade do Porto, Portugal Alfredo Costa --- University of Coimbra, PortugalThe 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... -
Order boundedness and order continuity properties of positive operator semigroups
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jochen Glück --- University of Wuppertal, School of Mathematics and Natural Sciences, Germany Michael Kaplin --- Institute of Mathematics, SlovenijaRelatively uniformly continuous (ruc) semigroups were recently introduced and studied by Kandic, Kramar-Fijavž, and the second-named author, in order to make the theory of one-parameter operator semigroups available in the setting of vector lattices, where no norm is present in... -
Stability analysis of fully dynamic piezoelectric beams with internal fractional delay
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Jianghao Hao --- Shanxi University, P.R. China Jing Yang --- Shanxi University, P.R. ChinaIn this paper, we are interested in the stability analysis of one-dimensional fully dynamic piezoelectric beam systems with internal fractional delay under different feedback controls (boundary and internal). By introducing two new equations to deal with fractional delay, equivalent new... -
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... -
The extended Frobenius problem for Lucas series incremented by a Lucas number
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Aureliano M. Robles-Pérez --- Universidad de Granada, Spain José Carlos Rosales --- Universidad de Granada, SpainWe 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... -
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, EcuadorThis 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... -
Numerical semigroups of coated odd elements
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M.B. Branco --- Universidade de Évora, J.C. Rosales --- Universidad de Granada, Spain M.A. Traesel --- Instituto Federal de São Paulo, BrazilA 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...