Results 31 to 40 of about 5,622,676 (84)
, 2012 In this thesis we consider in detail the following two fundamental problems for semigroup presentations: 1. Given a semigroup find a presentation defining it. 2. Given a presentation describe the semigroup defined by it.
Ruškuc, Nik
core +2 more sources
Idempotent structures in optimization [PDF]
, 2001 Consider the set A = R ∪ {+∞} with the binary operations o1 = max and o2 = + and denote by An the set of vectors v = (v1,...,vn) with entries in A. Let the generalised sum u o1 v of two vectors denote the vector with entries uj o1 vj , and the product
Kolokoltsov, V. N. (Vasiliĭ Nikitich)
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Presentations of inverse semigroups, their kernels and extensions [PDF]
, 2011 "Part of this work was done while Gray was an EPSRC Postdoctoral Research Fellow at the University of St Andrews, Scotland"Let S be an inverse semigroup and let π:S→T be a surjective homomorphism with kernel K.
Ruskuc, Nik +8 more
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Free idempotent generated semigroups over bands
, 2015 Free idempotent generated semigroups IG$(E)$, where $E$ is a biordered set, have provided a focus of recent research, the majority of the efforts concentrating on the behaviour of the maximal subgroups. Inspired by an example of Brittenham, Margolis and Meakin, several proofs have been offered that any group occurs as a maximal subgroup of some IG$(E)$,
Dandan, Yang, Gould, Victoria
openaire +2 more sources
Idempotent-generated semigroups and pseudovarieties [PDF]
, 2011 The operator which constructs the pseudovariety generated by the idempotent-generated semigroups of a given pseudovariety is investigated. Several relevant examples of pseudovarieties generated by their idempotent- generated elements are given as well as
Almeida, Jorge +3 more
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Algebraic singular functions are not always dense in the ideal of C∗$C^*$‐singular functions
Bulletin of the London Mathematical Society, Volume 58, Issue 5, May 2026.Abstract We give the first examples of étale (non‐Hausdorff) groupoids G$\mathcal {G}$ whose C∗$C^*$‐algebras contain singular elements that cannot be approximated by singular elements in Cc(G)$\mathcal {C}_c(\mathcal {G})$. We provide two examples: one is a bundle of groups and the other a minimal and effective groupoid constructed from a self‐similar
Diego Martínez, Nóra Szakács
wiley +1 more source
Jordan homomorphisms and T‐ideals
Journal of the London Mathematical Society, Volume 113, Issue 2, February 2026.Abstract Let A$A$ and B$B$ be associative algebras over a field F$F$ with char(F)≠2${\rm char}(F)\ne 2$. Our first main result states that if A$A$ is unital and equal to its commutator ideal, then every Jordan epimorphism φ:A→B$\varphi:A\rightarrow B$ is the sum of a homomorphism and an antihomomorphism. Our second main result concerns (not necessarily
Matej Brešar, Efim Zelmanov
wiley +1 more source
Nonstandard characterisations of tensor products and monads in the theory of ultrafilters
Mathematical Logic Quarterly, Volume 65, Issue 3, Page 347-369, October 2019., 2019 Abstract We use nonstandard methods, based on iterated hyperextensions, to develop applications to Ramsey theory of the theory of monads of ultrafilters. This is performed by studying in detail arbitrary tensor products of ultrafilters, as well as by characterising their combinatorial properties by means of their monads.
Lorenzo Luperi Baglini
wiley +1 more source
The variety generated by order algebras [PDF]
, 2002 Every ordered set can be considered as an algebra in a natural way. We investigate the variety generated by order algebras. We prove, among other things, that this variety is not finitely based and, although locally finite, it is not contained in any ...
Maróti, Miklós +5 more
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Fixed‐Point Hoop Algebras and Lattice‐Theoretic Properties of Derivation Classes
Journal of Mathematics, Volume 2026, Issue 1, 2026.We introduce three classes of derivations on hoop algebras—pseudo implicative, implicative, and f‐implicative—and investigate their algebraic characteristics through detailed examples. We establish that, under natural conditions, the collection of pseudo implicative derivations forms a bounded distributive lattice.
Ali Madanshekaf +2 more
wiley +1 more source