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In the context of (not necessarily minimal) actions, we consider the mean diameter and use it to characterize regular factor maps. Building on this characterization, we prove that an action is diam-mean equicontinuous if and only if it is a…

Dynamical Systems · Mathematics 2025-10-28 Till Hauser

For a finite group $G$, the representation dimension is the smallest integer realizable as the degree of a complex faithful representation of $G$. In this article, we compute representation dimension for some $p$-groups, their direct…

Group Theory · Mathematics 2023-08-04 Gurleen Kaur , Amit Kulshrestha , Anupam Singh

We show slow convergence of weighted ergodic averages for flows and actions of countable amenable groups.

Dynamical Systems · Mathematics 2025-05-27 Valery V. Ryzhikov

We show that every probability-measure-preserving action of a countable amenable group G can be tiled, modulo a null set, using finitely many finite subsets of G ("shapes") with prescribed approximate invariance so that the collection of…

Dynamical Systems · Mathematics 2020-01-20 Clinton T. Conley , Steve Jackson , David Kerr , Andrew Marks , Brandon Seward , Robin Tucker-Drob

We introduce inner amenability for discrete p.m.p. groupoids and investigate its basic properties, examples, and the connection with central sequences in the full group of the groupoid or central sequences in the von Neumann algebra…

Operator Algebras · Mathematics 2020-05-27 Yoshikata Kida , Robin Tucker-Drob

We show that for every integer $d$, there is a constant $N(d)$ such that if $K$ is any field and $F$ is a finite subset of $GL_d(K)$, which generates a non amenable subgroup, then $F^{N(d)}$ contains two elements, which freely generate a…

Group Theory · Mathematics 2008-04-10 Emmanuel Breuillard

We introduce a notion of entropy for automorphisms of discrete groups which admit amenable actions on a compact space. This entropy is dual to classical topological entropy in the sense that if G is discrete and abelian then our notion of…

Operator Algebras · Mathematics 2007-05-23 N. P. Brown , E. Germain

General arguments of Baumslag and Bieri guarantee that any metabelian group of finite Pr\"ufer rank can be embedded in a metabelian constructible group. Here, we consider the metric behavior of a rich class of examples and analyze the…

Group Theory · Mathematics 2018-03-28 Sean Cleary , Conchita Martínez-Pérez

Let $G$ be a locally compact group, and let $A_\cb(G)$ denote the closure of $A(G)$, the Fourier algebra of $G$, in the space of completely bounded multipliers of $A(G)$. If $G$ is a weakly amenable, discrete group such that $\cstar(G)$ is…

Functional Analysis · Mathematics 2007-10-12 Brian E. Forrest , Volker Runde , Nico Spronk

A measure preserving action of a countably infinite group \Gamma is called totally ergodic if every infinite subgroup of \Gamma acts ergodically. For example, all mixing and mildly mixing actions are totally ergodic. This note shows that if…

Dynamical Systems · Mathematics 2012-08-06 Robin Tucker-Drob

Coxeter groups admit amenable actions on compact spaces. Moreover, they have finite asymptotic dimension.

Geometric Topology · Mathematics 2007-05-23 A. N. Dranishnikov , T. Januszkiewicz

In this manuscript, we focus on the investigation of the BS dimension and BS packing dimension under amenable group actions. Firstly, we obtain a Bowen's equation which illustrate the relation of BS packing dimension to the packing…

Dynamical Systems · Mathematics 2025-07-08 Zhongxuan Yang

In this article, we establish maximal inequalities and deduce ergodic theorems for state-preserving actions of amenable, locally compact, second-countable groups on tracial non-commutative $L^1$-spaces. As a further consequence, in…

Operator Algebras · Mathematics 2026-01-01 Panchugopal Bikram , Hariharan G , Sudipta Kundu , Diptesh Saha

We study lattice embeddings for the class of countable groups $\Gamma$ defined by the property that the largest amenable uniformly recurrent subgroup $A_\Gamma$ is continuous. When $A_\Gamma$ comes from an extremely proximal action and the…

Group Theory · Mathematics 2020-12-23 Adrien Le Boudec

We show that a large class of i.c.c., countable, discrete groups satisfying a weak negative curvature condition are not inner amenable. By recent work of Hull and Osin, our result recovers that mapping class groups and Out(F_n) are not…

Operator Algebras · Mathematics 2019-02-20 Ionut Chifan , Thomas Sinclair , Bogdan Udrea

We prove that if G is a discrete group that admits a metrically proper action on a finite-dimensional CAT(0) cube complex X, then G is weakly amenable. We do this by constructing uniformly bounded Hilbert space representations for which the…

Operator Algebras · Mathematics 2007-05-23 Nigel Higson , Erik Guentner

We construct approximately inner actions of discrete amenable groups on strongly amenable subfactors of type II_1 with given invariants, and obtain classification results under some conditions. We also study the lifting of the relative \chi…

Operator Algebras · Mathematics 2007-05-23 Toshihiko Masuda

Let $G$ be a countable discrete amenable group, ${\cal M}$ a McDuff factor von Neumann algebra, and $A$ a separable nuclear weakly dense C$^*$-subalgebra of ${\cal M}$. We show that if two centrally free actions of $G$ on ${\cal M}$ differ…

Operator Algebras · Mathematics 2011-04-22 Yasuhiko Sato

In this work, we address ergodicity of smooth actions of finitely generated semi-groups on an m-dimensional closed manifold M. We provide sufficient conditions for such an action to be ergodic with respect to the Lebesgue measure. Our…

Dynamical Systems · Mathematics 2015-05-14 Azam Ehsani , Fatome-Helen Ghane , Marzie Zaj

We investigate the connection between the abelian rank of a countable amenable group and the existence of good averaging sequences (e.g. for the pointwise ergodic theorem). We show that if $G$ is a group of abelian rank $r(G)$ then any…

Dynamical Systems · Mathematics 2014-09-23 Michael Hochman