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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

We prove finiteness properties for groups of homeomorphisms that have finitely many "singular points", and we describe the normal structure of such groups. As an application, we prove that every countable abelian group can be embedded into…

Group Theory · Mathematics 2024-07-04 James Belk , James Hyde , Francesco Matucci

In this report we summarize this work, all finite simple groups $G$ can determined uniformly using their orders $|G|$ and the set $\pi_e(G)$ of their element orders.

Group Theory · Mathematics 2013-03-19 Wujie Shi

Let $G\curvearrowright T$ be a minimal action on an $\mathbb{R}$--tree with $G$ finitely presented. Assuming that $G$ is accessible over the family of arc-stabilisers of $T$, we give a description of the point-stabilisers of $T$ in terms of…

Group Theory · Mathematics 2026-03-13 Elia Fioravanti

Let $G$ be a residually finite, good group of finite virtual cohomological dimension. We prove that the natural monomorphism $G\hookrightarrow\hat{G}$ induces a bijective correspondence between conjugacy classes of finite $p$-subgroups of…

Group Theory · Mathematics 2024-10-29 Marco Boggi , Pavel Zalesskii

(Free-abelian)-by-free, self-similar groups generated by finite self-similar sets of tree automorphisms and having unsolvable conjugacy problem are constructed. Along the way, orbit undecidable, free subgroups of GL_d(Z), for d > 5, and…

Group Theory · Mathematics 2012-05-14 Zoran Sunic , Enric Ventura

The main result of this paper is the following theorem. Let q be a prime, A an elementary abelian group of order q^3. Suppose that A acts as a coprime group of automorphisms on a profinite group G in such a manner that C_G(a)' is periodic…

Group Theory · Mathematics 2011-08-03 C. Acciarri , A. de Souza Lima , P. Shumyatsky

Given a finitely generated relatively hyperbolic group $G$, we construct a finite generating set $X$ of $G$ such that $(G,X)$ has the `falsification by fellow traveler property' provided that the parabolic subgroups $\{H_\omega\}_{\omega\in…

Group Theory · Mathematics 2016-05-27 Yago Antolín , Laura Ciobanu

For $p\in\{2,3\}$ it is known that a saturated $p$-fusion system is realizable if and only if each of its components is realizable by a finite simple group. For primes $p\geq 5$ this is false. Building on work of Broto, M{\o}ller, Oliver…

Group Theory · Mathematics 2025-08-01 Ellen Henke , Justin Lynd

We show that every bounded automaton group can be embedded in a finitely generated, simple amenable group. The proof is based on the study of the topological full groups associated to the Schreier dynamical system of the mother groups. We…

Group Theory · Mathematics 2016-02-11 Nicolás Matte Bon

A group $G$ is said to have restricted centralizers if for each $g$ in $G$ the centralizer $C_G(g)$ either is finite or has finite index in $G$. Shalev showed that a profinite group with restricted centralizers is virtually abelian. Given a…

Group Theory · Mathematics 2021-12-30 Cristina Acciarri , Pavel Shumyatsky

We call a group $G$ {\it algorithmically finite} if no algorithm can produce an infinite set of pairwise distinct elements of $G$. We construct examples of recursively presented infinite algorithmically finite groups and study their…

Group Theory · Mathematics 2010-12-09 A. Myasnikov , D. Osin

We construct, for the first time, various types of specific non-special finite $p$-groups having abelian automorphism group. More specifically, we construct groups $G$ with abelian automorphism group such that $\gamma_2(G) < \mathrm{Z}(G) <…

Group Theory · Mathematics 2018-07-10 Vivek K. Jain , Pradeep K. Rai , Manoj K. Yadav

First we prove that any inner automorphism in the stabilizer of a graded-simple unital associative algebra whose grading group is abelian is the conjugation by a homogeneous element. Now consider a grading by an abelian group on an…

Rings and Algebras · Mathematics 2023-10-12 Adrián Rodrigo-Escudero

We give a geometric characterization of finite rational groups. In particular, we prove that a finite group is rational if and only if there exists a finite geometry $\Gamma$ of type $I$ and action of $G$ on $\Gamma$ as a group of…

Group Theory · Mathematics 2019-05-29 Cecil Andrew Ellard

Let $\mathcal G$ denote the space of finitely generated marked groups. For any finitely generated group $G$, we construct a continuous, injective map $f$ from the space of subgroups $Sub(G)$ to $\mathcal G$ that sends conjugate subgroups to…

Group Theory · Mathematics 2024-03-27 D. Osin

Let $\mathcal{C}$ be a class of finite groups closed for subgroups, quotients groups and extensions. Let $\Gamma$ be a finite simplicial graph and $G = G_{\Gamma}$ be the corresponding pro-$\mathcal C$ RAAG. We show that if $N$ is a…

Group Theory · Mathematics 2023-05-08 Dessislava Kochloukova , Pavel Zalesskii

Here we present a working framework to establish finite abelian groups in python. The primary aim is to allow new A-level students to work with examples of finite abelian groups using open source software. We include the code used in the…

Group Theory · Mathematics 2017-11-17 Paul Bradley , John Smethurst

Necessary and sufficient conditions for finite semihypergroups to be built from groups of the same order are established

Representation Theory · Mathematics 2017-03-06 Stan Onypchuk

We establish automatic realizations of Galois groups among groups M\rtimes G, where G is a cyclic group of order p^n for a prime p and M is a quotient of the group ring Fp[G].

Number Theory · Mathematics 2009-04-01 Jan Minac , Andrew Schultz , John Swallow