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1. 

   On *-Essential Ideals and Biideals of Rings with Involution

   Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: D.I.C. Mendes

   Let R be a ring with involution *. We describe the structure of R, when R has no proper *-essential *-ideals (*-biideals) and also when R has a *-essential minimal *-biideal.

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2. 

   Irreducibility in Pointfree Topology

   Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Themba Dube

   Irreducible spaces have been studied in topology by several authors. A. H. Stone introduced semi-irreducibility as a way of studying hereditarily compact spaces. In this paper we investigate these concepts in the context of frames.

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3. 

   ABSOLUTE RETRACTS AS REDUCED PRODUCTS

   Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M. Jenner --- Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, South Africa, P. Jipsen --- Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, South Africa, P. Ouwehand --- Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, South Africa, H. Rose --- Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, South Africa,

   We show that in finitely generated congruence distributive varieties every absolute retract is a product of reduced powers of maximal subdirectly irreducibles.

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4. 

   On G-character tables for normal subgroups

   Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: M.J. Felipe --- Instituto Universitario de Matemática Pura y Aplicada (IUMPA-UPV), Universitat Politècnica de València, Spain M.D. Pérez-Ramos --- Universitat de València, Spain V. Sotomayor --- Instituto Universitario de Matemática Pura y Aplicada (IUMPA-UPV), Universitat Politècnica de València, Spain

   Let N be a normal subgroup of a finite group G. From a result due to Brauer, it can be derived that the character table of G contains square submatrices which are induced by the G-conjugacy classes of elements in...

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5. 

   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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6. 

   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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7. 

   On SV_c -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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