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In this paper we study twisted conjugacy classes and the $R_{\infty}$-property for classical linear groups. In particular, we prove that the general linear group ${\rm GL}_n(K)$ and the special linear group ${\rm SL}_n(K)$ possess…

Group Theory · Mathematics 2012-02-01 T. R. Nasybullov

Let G be a group and {\phi} be an automorphism of G. Two elements x, y of G are said to be {\phi}-twisted if y = gx{\phi}(g)^{-1} for some g in G. We say that a group G has the R_{\infty}-property if the number of {\phi}-twisted conjugacy…

Group Theory · Mathematics 2025-10-06 Sushil Bhunia , Pinka Dey , Amit Roy

Reidemeister numbers of group automorphisms encode the number of twisted conjugacy classes of groups and might yield information about self-maps of spaces related to the given objects. Here we address a question posed by Gon\c{c}alves and…

Group Theory · Mathematics 2025-06-10 Paula Macedo Lins de Araujo , Yuri Santos Rego

A group is said to have the $R_\infty$ property if every automorphism has an infinite number of twisted conjugacy classes. We study the question whether $G$ has the $R_\infty$ property when $G$ is a finitely generated torsion-free nilpotent…

Group Theory · Mathematics 2011-05-11 Daciberg Gonçalves , Peter Wong

We say that a group has property $R_{\infty}$ if any group automorphism has an infinite number of twisted conjugacy classes. Fel'shtyn and Goncalves prove that the solvable Baumslag-Solitar groups BS(1,m) have property $R_{\infty}$. We…

Group Theory · Mathematics 2011-05-11 Jennifer Taback , Peter Wong

Given an automorphism $\phi:\Gamma\to \Gamma$, one has an action of $\Gamma$ on itself by $\phi$-twisted conjugacy, namely, $g.x=gx\phi(g^{-1})$. The orbits of this action are called $\phi$-twisted conjugacy classes. One says that $\Gamma$…

Group Theory · Mathematics 2019-08-15 T. Mubeena , P. Sankaran

We prove that Chevalley group over the field $F$ of zero characteristic possess $R_{\infty}$ property, if $F$ has torsion group of automorphisms or $F$ is an algebraically closed field which has finite transcendence degree over…

Group Theory · Mathematics 2015-02-27 T. R. Nasybullov

Let $G$ be a non-compact semisimple Lie group with finite centre and finitely many components. We show that any finitely generated group $\Gamma$ which is quasi-isometric to an irreducible lattice in $G$ has the $R_\infty$-property, namely,…

Group Theory · Mathematics 2018-01-09 T. Mubeena , P. Sankaran

We prove for residually finite groups the following long standing conjecture: the number of twisted conjugacy classes of an automorphism of a finitely generated group is equal (if it is finite) to the number of finite dimensional…

Group Theory · Mathematics 2012-05-01 Alexander Fel'shtyn , Evgenij Troitsky

We show that an accessible group with infinitely many ends has property $R_{\infty}$. That is, it has infinitely many twisted conjugacy classes for any twisting automorphism. We deduce that having property $R_{\infty}$ is undecidable…

Group Theory · Mathematics 2026-03-02 Francesco Fournier-Facio , Harry Iveson , Armando Martino , Wagner Sgobbi , Peter Wong

A group $G$ is said to have the property $R_\infty$ if every automorphism $\phi \in {\rm Aut}(G)$ has an infinite number of $\phi$-twisted conjugacy classes. Recent work of Gon\c{c}alves and Kochloukova uses the $\Sigma^n$…

Group Theory · Mathematics 2011-05-11 Nic Koban , Peter Wong

Let $f$ be an automorphism of a group $G$. Two elements $x, y$ in $G$ are said to be in the same $f$-twisted conjugacy class if there exists an element $z$ in $G$ such that $y=z x f(z^{-1})$. This is an equivalence relation known as…

Group Theory · Mathematics 2013-12-10 Daciberg L. Gonçalves , Parameswaran Sankaran

Let $\Gamma_d(q)$ denote the group whose Cayley graph with respect to a particular generating set is the Diestel-Leader graph $DL_d(q)$, as described by Bartholdi, Neuhauser and Woess. We compute both $Aut(\Gamma_d(q))$ and…

Group Theory · Mathematics 2015-02-03 Melanie Stein , Jennifer Taback , Peter Wong

In this paper, generalising the idea of the Rokhlin property, we explore the concept of the twisted Rokhlin property of topological groups. A topological group is said to exhibit the twisted Rokhlin property if, for each automorphism $\phi$…

Geometric Topology · Mathematics 2026-02-04 Pravin Kumar , Apeksha Sanghi , Mahender Singh

A group $G$ has property $R_\infty$ if for every $\phi\in Aut(G)$, there are an infinite number of $\phi$-twisted conjugacy classes of elements in $G$. In this note, we determine the $R_\infty$-property for $G=\pi_1(M)$ for all geometric…

Group Theory · Mathematics 2020-06-02 Daciberg Gonçalves , Parameswaran Sankaran , Peter Wong

Let F be a field of characteristic not 2 and assume all algebras are over F. We establish several conjugacy theorems for the special linear Lie algebra sl_2 over an F-algebra which is a UFD. We find the structure of the full automorphism…

Rings and Algebras · Mathematics 2016-09-07 Stephen Berman , Jun Morita

We say that $x,y\in \Gamma$ are in the same $\phi$-twisted conjugacy class and write $x\sim_\phi y$ if there exists an element $\gamma\in \Gamma$ such that $y=\gamma x\phi(\gamma^{-1})$. This is an equivalence relation on $\Gamma$ called…

Group Theory · Mathematics 2014-12-30 Daciberg Gonçalves , Parameswaran Sankaran

In this paper we consider some classical varieties of linear algebras over the field which has characteristic 0. For every considered variety we take a category of the finite generated free algebras of this variety. And for every this…

Rings and Algebras · Mathematics 2012-10-25 A. Tsurkov

A group $G$ is said to have property $R_{\infty}$ if for every automorphism $\varphi \in {\rm Aut}(G)$, the cardinality of the set of $\varphi$-twisted conjugacy classes is infinite. Many classes of groups are known to have such property.…

Group Theory · Mathematics 2021-08-03 Parameswaran Sankaran , Peter Wong

The aim of this note is to show that the automorphism and isometry groups of the C*-algebra $\l_\infty(N,B(H))$ of all bounded sequences in $B(H)$ are topologically reflexive which, as one of our former results shows, is not the case with…

Functional Analysis · Mathematics 2008-02-03 Lajos Molnar
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