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We study equalizers and fixed points of monomorphisms of free groups at infinity. We show that the action of the equalizer of two monomorphisms on the regular points of the equalizer at infinity has finitely many orbits, showing that the…

Group Theory · Mathematics 2026-04-02 André Carvalho , Pedro V. Silva

We describe a procedure for constructing a generalized Thompson group out of a family of groups that is equipped with what we call a cloning system. The previously known Thompson groups F, V, Vbr and Fbr arise from this procedure using,…

Group Theory · Mathematics 2018-10-25 Stefan Witzel , Matthew C. B. Zaremsky

We show that for soluble groups of type FPn, centralisers of finite subgroups need not be of type FPn.

Group Theory · Mathematics 2009-03-25 D. H. Kochloukova , C. Martinez-Perez , B. E. A. Nucinkis

It is proved that if a finite group $G$ has an automorphism of order $n$ with $m$ fixed points, then $G$ has a soluble subgroup whose index and Fitting height are bounded in terms of $m$ and $n$. As a corollary, a problem of B. Hartley is…

Group Theory · Mathematics 2025-08-21 Evgeny Khukhro

This paper investigates the finite generation of cluster automorphism groups. By applying the pseudo $\mathbb{N}$-grading introduced in our previous work, we establish a sufficient condition for a cluster automorphism group to be finitely…

Rings and Algebras · Mathematics 2026-05-28 Changjian Fu , Zhanhong Liang , Yinzhi Wang

We consider generalisations of Thompson's group $V$, denoted by $V_r(\Sigma)$, which also include the groups of Higman, Stein and Brin. It was shown by the authors in [20] that under some mild conditions these groups and centralisers of…

Group Theory · Mathematics 2018-07-25 Conchita Martínez-Pérez , Francesco Matucci , Brita E. A. Nucinkis

In this paper we consider local centralizer classification and rigidity of some toral automorphisms. In low dimensions we classify up to finite index possible centralizers for volume preserving diffeomorphisms $f$ $C^{1}-$close to an…

Dynamical Systems · Mathematics 2024-10-07 Sven Sandfeldt

We describe structure of locally finite groups of finite centraliser dimension.

Group Theory · Mathematics 2019-01-31 Alexandre Borovik , Ulla Karhumäki

We prove that infinite definably simple locally finite groups of finite centraliser dimension are simple groups of Lie type over locally finite fields. Then, we identify conditions on automorphisms of a stable group that make it resemble…

Logic · Mathematics 2019-06-12 Ulla Karhumäki

We propose a new unifying framework for Thompson-like groups using a well-known device called operads and category theory as language. We discuss examples of operad groups which have appeared in the literature before. As a first…

Group Theory · Mathematics 2016-04-05 Werner Thumann

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

The goal of this paper is to characterization generalized Alexander quandles of finite groups in the language of the underlying groups. Firstly, we prove that if finite groups $G$ are simple, then the quandle isomorphic classes of…

Group Theory · Mathematics 2022-11-01 Akihiro Higashitani , Hirotake Kurihara

The classical result by Dyer--Scott about fixed subgroups of finite order automorphisms of $F_n$ being free factors of $F_n$ is no longer true in $Z^m\times F_n$. Within this more general context, we prove a relaxed version in the spirit of…

Group Theory · Mathematics 2019-06-06 Mallika Roy , Enric Ventura

We study finite groups $G$ with elements $g$ such that $\lvert \mathbf{C}_G(g)\rvert = \lvert G:G' \rvert$. (Such elements generalize fixed-point-free automorphisms of finite groups.) We show that these groups have a unique conjugacy class…

Group Theory · Mathematics 2023-05-11 Frieder Ladisch

The generalised Fitting subgroup of a finite group is the group generated by all subnormal subgroups that are either nilpotent or quasisimple. The importance of this subgroup in finite group theory stems from the fact that it always…

Group Theory · Mathematics 2009-04-03 Colin Reid

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 investigate fixed subgroups of automorphisms of generalised Baumslag-Solitar (GBS) groups. Our main results are for automorphisms leaving a Bass-Serre tree invariant, under the assumption that all edge stabilisers are strictly contained…

Group Theory · Mathematics 2025-10-15 Oli Jones , Alan Logan

A group is said to be stable if it is isomorphic to its automorphism group. We investigate how we can extend centerless groups to construct finite stable groups with nontrivial centers. To this end, we classify all finite stable groups…

Group Theory · Mathematics 2026-05-05 Isaac Ochoa

The aim of this note is to explain a generalization to the real case of a well known result on the automorphism group of an unbounded tube type symmetric domain in a complex vector space of finite dimension.

Differential Geometry · Mathematics 2010-12-07 Fernando De Oliveira

Given a closed smooth manifold $M$ of even dimension $2n\ge6$ with finite fundamental group, we show that the classifying space ${\rm BDiff}(M)$ of the diffeomorphism group of $M$ is of finite type and has finitely generated homotopy groups…

Algebraic Topology · Mathematics 2023-02-20 Mauricio Bustamante , Manuel Krannich , Alexander Kupers