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We give a survey of recent results related to the problem of characterizing finite-dimensional division algebras by the set of isomorphism classes of their maximal subfields. We also discuss various generalizations of this problem and some…

Rings and Algebras · Mathematics 2015-06-11 Vladimir I. Chernousov , Andrei S. Rapinchuk , Igor A. Rapinchuk

In this paper, we study the relationship between the mapping class group of an infinite-type surface and the simultaneous flip graph, a variant of the flip graph for infinite-type surfaces defined by Fossas and Parlier. We show that the…

Geometric Topology · Mathematics 2022-01-28 Assaf Bar-Natan , Advay Goel , Brendan Halstead , Paul Hamrick , Sumedh Shenoy , Rishi Verma

If $G$ is a finite group and $k =q>2$ or $k=q+1$ for a prime power $q$ then, for infinitely many integers $v$, there is a $2$-$(v,k,1)$-design ${\bf D}$ for which ${\rm Aut} {\bf D}\cong G$.

Combinatorics · Mathematics 2018-10-16 William M. Kantor

We study the automorphism groups of finite-dimensional cyclic Leibniz algebras. In this connection, we consider the relationships between groups, modules over associative rings and Leibniz algebras.

Rings and Algebras · Mathematics 2021-08-21 Leonid A. Kurdachenko , Aleksandr A. Pypka , Igor Ya. Subbotin

In this paper, we discuss a group-theoretical generalization of the well-known Gauss formula involving the functionthat counts the number of automorphisms of a finite group. This gives several characterizations of finite cyclic groups.

Group Theory · Mathematics 2022-12-20 Georgiana Fasolă , Marius Tărnăuceanu

We describe the exponential map from an infinite-dimensional Lie algebra to an infinite-dimensional group of operators on a Hilbert space. Notions of differential geometry are introduced for these groups. In particular, the Ricci curvature,…

Differential Geometry · Mathematics 2007-05-23 Maria Gordina

We establish links between countable algebraically closed graphs and the endomorphisms of the countable universal graph $R$. As a consequence we show that, for any countable graph $\Gamma$, there are uncountably many maximal subgroups of…

Combinatorics · Mathematics 2016-04-06 Igor Dolinka , Robert D. Gray , Jillian D. McPhee , James D. Mitchell , Martyn Quick

Let G be a finitely generated relatively hyperbolic group. We show that if no peripheral subgroup of G is hyperbolic relative to a collection of proper subgroups, then the fixed subgroup of every automorphism of G is relatively quasiconvex.…

Group Theory · Mathematics 2012-11-06 Ashot Minasyan , Denis Osin

We study infinite groups interpretable in three families of valued fields: $V$-minimal, power bounded $T$-convex, and $p$-adically closed fields. We show that every such group $G$ has unbounded exponent and that if $G$ is dp-minimal then it…

Logic · Mathematics 2024-04-09 Yatir Halevi , Assaf Hasson , Ya'acov Peterzil

We show that, for each finite algebra A, either it has symmetric term operations of all arities or else some finite algebra in the variety generated by A has two automorphisms without a common fixed point. We also show this two-automorphism…

Rings and Algebras · Mathematics 2016-05-16 Catarina Carvalho , Andrei Krokhin

Bumagin-Wise posed the question of whether every countable group can be realised as the outer automorphism group of a finitely generated, residually finite group. We give a partial answer to this problem for recursively presentable groups.

Group Theory · Mathematics 2018-10-25 Alan D. Logan

A self-similar group of finite type is the profinite group of all automorphisms of a regular rooted tree that locally around every vertex act as elements of a given finite group of allowed actions. We provide criteria for determining when a…

Group Theory · Mathematics 2014-09-02 Ievgen V. Bondarenko , Igor O. Samoilovych

We characterize the groups isomorphic to full automorphism groups of ordered abelian groups. The result will follow from classical theorems on ordered groups adding an argument from proofs used to realize rings as endomorphism rings of…

Logic · Mathematics 2007-05-23 Rüdiger Göbel , Saharon Shelah

Elder, Kambites, and Ostheimer showed that if the word problem of a finitely generated group $H$ is accepted by a $G$-automaton for an abelian group $G$, then $H$ is virtually abelian. We give a new, elementary, and purely combinatorial…

Group Theory · Mathematics 2022-11-01 Takao Yuyama

It is known that every finite group can be represented as the full group of automorphisms of a suitable compact dessin d'enfant. In this paper, we give a constructive and easy proof that the same holds for any countable group by considering…

Group Theory · Mathematics 2022-06-09 Alejandro Cañas , Ruben A. Hidalgo , Francisco Javier Turiel , Antonio Viruel

We prove that if the group of fixed points of a generic automorphism of a simple group of finite Morley rank is pseudofinite, then this group is an extension of a (twisted) Chevalley group over a pseudofinite field. On the way to obtain…

Group Theory · Mathematics 2012-01-31 Pınar Uğurlu

We show that any Kahler extension of a finitely generated abelian group by a surface group of genus g at least 2 is virtually a product. Conversely, we prove that any homomorphism of an even rank, finitely generated abelian group into the…

Geometric Topology · Mathematics 2016-11-29 Corey Bregman , Letao Zhang

We prove that in dimensions not equal to 4, 5, or 7, the homology and homotopy groups of the classifying space of the topological group of diffeomorphisms of a disk fixing the boundary are finitely generated in each degree. The proof uses…

Algebraic Topology · Mathematics 2019-10-23 Alexander Kupers

We give strengthened versions of the Herwig-Lascar and Hodkinson-Otto extension theorems for partial automorphisms of finite structures. Such strengthenings yield several combinatorial and group-theoretic consequences for homogeneous…

Logic · Mathematics 2019-04-17 Daoud Siniora , Sławomir Solecki

It is shown, for a given graph group $G$, that the fixed point subgroup Fix$\,\varphi$ is finitely generated for every endomorphism $\varphi$ of $G$ if and only if $G$ is a free product of free abelian groups. The same conditions hold for…

Group Theory · Mathematics 2013-10-29 Emanuele Rodaro , Pedro V. Silva , Mihalis Sykiotis