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We give a technical result that implies a straightforward necessary and sufficient conditions for a graph of groups with virtually cyclic edge groups to be one ended. For arbitrary graphs of groups, we show that if their fundamental group…

Group Theory · Mathematics 2016-01-20 Nicholas Touikan

We study finite subgroups of outer automorphisms of free products. We give upper bounds for the orders of these finite subgroups as well as bounds for the orders of individual torsion outer automorphisms under some (necessary) conditions…

Group Theory · Mathematics 2025-06-23 Ioannis Papavasileiou , Dionysios Syrigos

We describe computational results about undirected graphs having $10$ vertices and automorphism group isomorphic to $\mathbb{Z}/4\mathbb{Z}$.

Combinatorics · Mathematics 2015-04-06 Peteris Daugulis

When $S$ is a closed, orientable surface with genus $g(S) \geq 2$, we show that the automorphism group of the compression body graph $\mathcal{CB}(S)$ is the mapping class group. Here, vertices are compression bodies with exterior boundary…

Geometric Topology · Mathematics 2024-03-11 Ian Biringer , Nicholas G. Vlamis

We study properties of automorphisms of graph products of groups. We show that graph product $\Gamma\mathcal{G}$ has non-trivial pointwise inner automorphisms if and only if some vertex group corresponding to a central vertex has…

Group Theory · Mathematics 2016-10-13 Michal Ferov

We consider the size and structure of the automorphism groups of a variety of empirical `real-world' networks and find that, in contrast to classical random graph models, many real-world networks are richly symmetric. We relate automorphism…

Physics and Society · Physics 2020-08-05 Ben D. MacArthur , Rubén J. Sánchez-García , James W. Anderson

Consider a smooth connected algebraic group $G$ acting on a normal projective variety $X$ with an open dense orbit. We show that Aut($X$) is a linear algebraic group if so is $G$; for an arbitrary $G$, the group of components of Aut($X$) is…

Algebraic Geometry · Mathematics 2019-11-21 Michel Brion

The main result of this paper is that the outer automorphism group of a free product of finite groups and cyclic groups is semistable at infinity (provided it is one ended) or semistable at each end. In a previous paper, we showed that the…

Group Theory · Mathematics 2025-03-10 Rylee Alanza Lyman

Given a positive definite even lattice and a commutative ring, there is a standard construction of a lattice vertex algebra over the commutative ring, and it admits a natural grading by non-negative integers. We describe the groups of…

Quantum Algebra · Mathematics 2026-02-18 Scott Carnahan , Hayate Kobayashi

We describe an underlying right angled building structure of any graph product of buildings. We describe the automorphism group of the graph product of buildings. We show that the notion of generalized graph product of a collection of…

Group Theory · Mathematics 2014-07-18 Aliska Gibbins

We show that every virtually torsion-free subgroup of the outer automorphism group of a conjugacy separable relatively hyperbolic group is residually finite. As a direct consequence, we obtain that the outer automorphism group of a limit…

Group Theory · Mathematics 2009-07-29 V. Metaftsis , M. Sykiotis

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

In this paper, we briefly review some of the known results concerning the cohomological structures of the mapping class group of surfaces, the outer automorphism group of free groups, the diffeomorphism group of surfaces as well as various…

Geometric Topology · Mathematics 2007-05-23 Shigeyuki Morita

Given a finite graph G there is a corresponding group given by the presentation with generators the vertices of G and a relation [x,y]=1 for generators x and y precisely when (x,y) is an edge of G. Such groups are known as partially…

Group Theory · Mathematics 2007-07-03 Andrew J Duncan , Ilya V Kazachkov , Vladimir N Remeslennikov

We classify all group topologies coarser than the topology of stabilizers of finite sets in the case of automorphism groups of countable free-homogeneous structures, Urysohn space and Urysohn sphere, among other related results.

Logic · Mathematics 2024-02-21 Zaniar Ghadernezhad , Javier de la Nuez González

Let $G$ be a group. The directed endomorphism graph, \dend of $G$ is a directed graph with vertex set $G$ and there is a directed edge from the vertex `$a$' to the vertex `$\, b$' $(a \neq b) $ if and only if there exists an endomorphism on…

Combinatorics · Mathematics 2025-12-16 Midhuna V Ajith , Mainak Ghosh , Aparna Lakshmanan S

The fundamental group of a finite graph of groups with trivial edge groups is a free product. We are interested in those outer automorphisms of such a free product that permute the conjugacy classes of the vertex groups. We show that in…

Group Theory · Mathematics 2022-03-18 Rylee Alanza Lyman

The group ring of the automorphism group of a p-group is studied using the automorphism groups of subgroups and quotient groups of P.

Representation Theory · Mathematics 2007-11-12 John Martino , Stewart Priddy

In this article we study automorphisms of Toeplitz subshifts. Such groups are abelian and any finitely generated torsion subgroup is finite and cyclic. When the complexity is non superlinear, we prove that the automorphism group is, modulo…

Dynamical Systems · Mathematics 2017-06-15 Sebastián Donoso , Fabien Durand , Alejandro Maass , Samuel Petite

We derive a formula connecting the orders of the automorphism groups of a finite group and of its covering groups.

Group Theory · Mathematics 2017-07-21 Avinoam Mann