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For a mixing shift of finite type, the associated automorphism group has a rich algebraic structure, and yet we have few criteria to distinguish when two such groups are isomorphic. We introduce a stabilization of the automorphism group,…

Dynamical Systems · Mathematics 2020-01-28 Yair Hartman , Bryna Kra , Scott Schmieding

We classify all finite 2-groups that have a cyclic or dihedral maximal subgroup and determine their automorphism groups. Based on this result, we classify all pairs $ (G,\mathcal{M}) $, such that $ G $ is a finite 2-group and $ \mathcal{M}…

Group Theory · Mathematics 2025-08-11 Peice Hua

We give an algorithm for finding the index of a positive outer automorphism of the free group, and prove the algorithm exits in a finite time.

Group Theory · Mathematics 2012-03-01 Yann Jullian

Complex hyperbolic triangle groups were first considered by Mostow in building the first nonarithmetic lattices in PU(2, 1). They are a natural generalization of the classical triangle groups acting on the hyperbolic plane. A well-known…

Geometric Topology · Mathematics 2011-12-09 Matthew Stover

In this paper we initiate the study of cyclic algebraic geometry codes. We give conditions to construct cyclic algebraic geometry codes in the context of algebraic function fields over a finite field by using their group of automorphisms.…

Algebraic Geometry · Mathematics 2021-06-17 Gustavo Cabaña , María Chara , Ricardo A. Podestá , Ricardo Toledano

We determine the automorphism group for some well known constructions of finite semifields. In particular, we compute the automorphism group of Sandler's semifields and in certain cases the automorphism groups of the Hughes-Kleinfeld and…

Rings and Algebras · Mathematics 2013-05-23 Andrew Steele

We compute Aut(W) for any even Coxeter group whose Coxeter diagram is connected, contains no edges labeled 2, and cannot be separated into more than 2 connected components by removing a single vertex. The description is given explicitly in…

Group Theory · Mathematics 2007-05-23 Patrick Bahls

We study the automorphism group of the algebraic closure of a substructure A of a pseudo-finite field F, or more generally, of a bounded PAC field F. This paper answers some of the questions of [1], and in particular that any finite group…

Logic · Mathematics 2016-02-26 Özlem Beyarslan , Zoé Chatzidakis

We study the acylindrical hyperbolicity of the outer automorphism group of a right-angled Artin group $A_\Gamma$. When the defining graph $\Gamma$ has no SIL-pair (separating intersection of links), we obtain a necessary and sufficient…

Group Theory · Mathematics 2026-05-05 Hyungryul Baik , Junseok Kim

We compute the automorphism group of the intersection graph of many large-type Artin groups. This graph is an analogue of the curve graph of mapping class groups but in the context of Artin groups. As an application, we deduce a number of…

Group Theory · Mathematics 2024-07-30 Jingyin Huang , Damian Osajda , Nicolas Vaskou

For a locally finite, connected graph $\Gamma$, let $\operatorname{Map}(\Gamma)$ denote the group of proper homotopy equivalences of $\Gamma$ up to proper homotopy. Excluding sporadic cases, we show $\operatorname{Aut}(S(M_\Gamma)) \cong…

Geometric Topology · Mathematics 2024-10-10 Thomas Hill , Michael C. Kopreski , Rebecca Rechkin , George Shaji , Brian Udall

We show that every finite group occurs as the automorphism group of infinitely many finite (field) extensions of any given Hilbertian field. This extends and unifies previous results of M. Fried and Takahashi on the global field case.

Number Theory · Mathematics 2017-12-19 François Legrand , Elad Paran

The main purpose of this paper is to describe some published results and outline corresponding approaches which when applied to automorphism groups of algebras or groups establish that these groups are linear or non-linear.

Group Theory · Mathematics 2017-09-28 Vitalii Roman'kov

Last years a number of papers were devoted to describing automorphisms of semigroups of endomorphisms of free finitely generated universal algebras of some varieties: groups, semigroups, associative commutative algebras, inverse semigroups,…

General Mathematics · Mathematics 2007-05-23 Grigori Zhitomirski

We determine the group structure of the homotopy set whose target is the automorphism group of the Cuntz algebra $O_{n+1}$ for finite n in terms of K-theory. We show that there is an example of a space for which the homotopy set is a…

Operator Algebras · Mathematics 2019-03-13 Masaki Izumi , Taro Sogabe

We show that the isomorphism problem is solvable in the class of central extensions of word-hyperbolic groups, and that the isomorphism problem for biautomatic groups reduces to that for biautomatic groups with finite centre. We describe an…

Geometric Topology · Mathematics 2015-05-27 Martin R. Bridson , Lawrence Reeves

We consider the Macdonald group $\langle x,y\,|\, x^{[x,y]}=x^{1+2^m\ell},\, y^{[y,x]}=y^{1+2^m\ell}\rangle$ and its Sylow 2-subgroup $J=\langle x,y\,|\, x^{[x,y]}=x^{1+2^m\ell},\, y^{[y,x]}=y^{1+2^m\ell},…

Group Theory · Mathematics 2024-01-31 Alexander Montoya Ocampo , Fernando Szechtman

The group of 2-by-2 matrices with integer entries and determinant $\pm > 1$ can be identified either with the group of outer automorphisms of a rank two free group or with the group of isotopy classes of homeomorphisms of a 2-dimensional…

Group Theory · Mathematics 2007-05-23 Martin R Bridson , Karen Vogtmann

For a finite group G of Lie type and a prime p, we compare the automorphism groups of the fusion and linking systems of G at p with the automorphism group of G itself. When p is the defining characteristic of G, they are all isomorphic,…

Group Theory · Mathematics 2016-01-19 Carles Broto , Jesper M. Møller , Bob Oliver

In this work, we study three families of locally graded groups with finitely many orbits under automorphisms. We prove that: (i) a residually finite group with finitely many orbits under automorphisms is locally finite and has finite…

Group Theory · Mathematics 2026-05-05 Alex Carrazedo Dantas , Jucélia Ferreira de Sousa