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We exhibit examples of finitely presented subgroups $P$ of direct products of hyperbolic groups for which there is no algorithm that detects whether a finitely presented group has a quotient isomorphic to $P$. For any torsion-free, linear,…

Group Theory · Mathematics 2025-12-30 Konstantinos Tsouvalas

We provide an explicit construction for a complete set of orthogonal primitive idempotents of finite group algebras over nilpotent groups. Furthermore, we give a complete set of matrix units in each simple epimorphic image of a finite group…

Representation Theory · Mathematics 2013-02-19 Inneke Van Gelder , Gabriela Olteanu

We study the complexity of the isomorphism relation for various classes of closed subgroups of the group of permutations of the natural numbers. We use the setting of Borel reducibility between equivalence relations on Polish spaces. For…

Logic · Mathematics 2021-08-24 Alexander S. Kechris , Andree Nies , Katrin Tent

We show that there exists an algorithm to decide any single equation in the Heisenberg group in finite time. The method works for all two-step nilpotent groups with rank-one commutator, which includes the higher Heisenberg groups. We also…

Group Theory · Mathematics 2014-01-14 Moon Duchin , Hao Liang , Michael Shapiro

This is a survey on the automorphism groups in various classes of affine algebraic surfaces and the algebraic group actions on such surfaces. Being infinite-dimensional, these automorphism groups share some important features of algebraic…

Algebraic Geometry · Mathematics 2025-03-06 Sergei Kovalenko , Alexander Perepechko , Mikhail Zaidenberg

A group $G$ is integrable if it is isomorphic to the derived subgroup of a group $H$; that is, if $H'\simeq G$, and in this case $H$ is an integral of $G$. If $G$ is a subgroup of $U$, we say that $G$ is integrable within $U$ if $G=H'$ for…

Group Theory · Mathematics 2022-07-08 Russell Blyth , Francesco Fumagalli , Francesco Matucci

In this paper we give an algorithm to determine all finite matrix groups over a number field. Our algorithm is based on the representation theory of finite groups.

Group Theory · Mathematics 2025-11-11 Daniil Yurshevich

The first part of the paper centers in the study of embeddability between partially commutative groups. In [KK], for a finite simplicial graph $\Gamma$, the authors introduce an infinite, locally infinite graph $\Gamma^e$, called the…

Group Theory · Mathematics 2015-06-11 Montserrat Casals-Ruiz

We consider classes of fundamental groups of complements of various kinds of codimension 2 embeddings and show that, in general, the problem of deciding whether or not a group in one class belongs to a smaller class is algorithmically…

Group Theory · Mathematics 2009-08-28 F. Gonzalez-Acuna , C. McA. Gordon , J. Simon

The goal of this paper is to study primitive groups that are contained in the union of maximal (in the symmetric group) imprimitive groups. The study of types of permutations that appear inside primitive groups goes back to the origins of…

Group Theory · Mathematics 2016-11-25 J. Araújo , J. P. Araújo , P. J. Cameron , T. Dobson , A. Hulpke , P. Lopes

We prove that there exist finitely presented, residually finite groups that are profinitely rigid in the class of all finitely presented groups but not in the class of all finitely generated groups. These groups are of the form $\Gamma…

Group Theory · Mathematics 2025-04-15 M. R. Bridson , A. W. Reid , R. Spitler

Let V_* be the normalized unitary subgroup of the modular group algebra FG of a finite p-group G over a finite field F with the classical involution *. We investigate the isomorphism problem for the group V_*, that asks when the group V_*…

Rings and Algebras · Mathematics 2020-05-20 Zsolt Balogh , Victor Bovdi

A complete classification is given of finite groups whose elements are partitioned into three orbits by the automorphism groups, solving the long-standing classification problem initiated by G. Higman in 1963. As a consequence, a…

Group Theory · Mathematics 2025-05-07 Cai Heng Li , Yan Zhou Zhu

We suggest a new approach to the study of relatively hyperbolic groups based on relative isoperimetric inequalities. Various geometric, algebraic, and algorithmic properties are discussed.

Group Theory · Mathematics 2015-01-29 D. V. Osin

Let $G$ be a finitely generated solvable-by-finite linear group. We present an algorithm to compute the torsion-free rank of $G$ and a bound on the Pr\"{u}fer rank of $G$. This yields in turn an algorithm to decide whether a finitely…

Group Theory · Mathematics 2019-05-14 A. S. Detinko , D. L. Flannery , E. A. O'Brien

We present a new algorithm deciding if the intersection of a quasiconvex subgroup of a negatively curved group with a conjugate is finite. We also give a short proof of decidability of the membership problem for quasiconvex subgroups of…

Group Theory · Mathematics 2018-11-08 Rita Gitik

We consider the problem of realizing a group as the fundamental group of a graph of groups where the vertex groups are restricted to certain classes (for example, coming from a certain finite list of groups, or having bounded geometric…

Geometric Topology · Mathematics 2021-09-15 Nic Brody , Michael R. Klug

We describe a new approach towards the systematic construction of finite groups up to isomorphism. This approach yields a practical algorithm for the construction of finite solvable groups up to isomorphism. We report on a GAP…

Group Theory · Mathematics 2016-07-18 Bettina Eick , Max Horn

This survey paper concerns mainly with some asymptotic topological properties of finitely presented discrete groups: quasi-simple filtration (QSF), geometric simple connectivity (GSC), topological inverse-representations, and the notion of…

Geometric Topology · Mathematics 2018-04-17 Daniele Ettore Otera , Valentin Poénaru

We introduce the notion of semigroup with a tight ideal series and investigate their closures in semitopological semigroups, particularly inverse semigroups with continuous inversion. As a corollary we show that the symmetric inverse…

Group Theory · Mathematics 2009-03-19 Oleg Gutik , Jimmie Lawson , Dušan Repovš