Results 31 to 40 of about 5,621,789 (82)
Subsemigroups of virtually free groups : finite Malcev presentations and testing for freeness [PDF]
, 2006 This paper shows that, given a finite subset X of a finitely generated virtually free group F, the freeness of the subsemigroup of F generated by X can be tested algorithmically. (A group is virtually free if it contains a free subgroup of finite index.)
Robertson, Edmund Frederick +2 more
core +1 more source
Free idempotent generated semigroups [PDF]
, 2014 The study of the free idempotent generated semigroup IG$(E)$ over a biordered set $E$ began with the seminal work of Nambooripad in the 1970s and has seen a recent revival with a number of new approaches, both geometric and combinatorial.
YANG, DANDAN
core +6 more sources
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 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)
core +1 more source
On generators, relations and D-simplicity of direct products, Byleen extensions, and other semigroup constructions [PDF]
, 2015 In this thesis we study two different topics, both in the context of semigroup constructions. The first is the investigation of an embedding problem, specifically the problem of whether it is possible to embed any given finitely presentable semigroup ...
Baynes, Samuel
core +2 more sources
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
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
An Improved Computationally Efficient Method for Finding the Drazin Inverse
Discrete Dynamics in Nature and Society, Volume 2018, Issue 1, 2018., 2018 Drazin inverse is one of the most significant inverses in the matrix theory, where its computation is an intensive and useful task. The objective of this work is to propose a computationally effective iterative scheme for finding the Drazin inverse. The convergence is investigated analytically by applying a suitable initial matrix.
Haifa Bin Jebreen +2 more
wiley +1 more source