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Let $F\subseteq H\subseteq G$ be closed subgroups of a locally compact group. In response to a 1972 question by Eymard, we construct an example where the homogeneous factor-space $G/F$ is amenable in the sense of Eymard-Greenleaf, while…

Operator Algebras · Mathematics 2007-09-03 Vladimir Pestov

Approximate algebraic structures play a defining role in arithmetic combinatorics and have found remarkable applications to basic questions in number theory and pseudorandomness. Here we study approximate representations of finite groups:…

Representation Theory · Mathematics 2010-10-01 Cristopher Moore , Alexander Russell

We show that generalised time-frequency shifts on the Heisenberg group $\mathbf{H}_n \cong \mathbb{R}^{2n+1}$, realised as a unitary irreducible representation of a nilpotent Lie group acting on $L^{2}(\mathbf{H}_n)$, give rise to a novel…

Functional Analysis · Mathematics 2018-12-20 Véronique Fischer , David Rottensteiner , Michael Ruzhansky

For a group $G$ first order definable in a structure $M$, we continue the study of the "definable topological dynamics" of $G$. The special case when all subsets of $G$ are definable in the given structure $M$ is simply the usual…

Logic · Mathematics 2016-10-11 Krzysztof Krupinski , Anand Pillay

We study continuous bounded cohomology of totally disconnected locally compact groups with coefficients in a non-Archimedean valued field $K$. To capture the features of classical amenability that induce the vanishing of real bounded…

Group Theory · Mathematics 2022-04-29 Francesco Fournier-Facio

We study amenability of affine algebras (based on the notion of almost-invariant finite-dimensional subspace), and apply it to algebras associated with finitely generated groups. We show that a group G is amenable if and only if its group…

Group Theory · Mathematics 2009-11-27 Laurent Bartholdi

We study actions of discrete groups on Hilbert $C^*$-modules induced from topological actions on compact Hausdorff spaces. We show non-amenability of actions of non-amenable and non-a-T-menable groups, provided there exists a…

Functional Analysis · Mathematics 2011-08-09 Ronald G. Douglas , Piotr W. Nowak

We study the automorphism groups of countable homogeneous directed graphs (and some additional homogeneous structures) from the point of view of topological dynamics. We determine precisely which of these automorphism groups are amenable…

Combinatorics · Mathematics 2017-12-29 Micheal Pawliuk , Miodrag Sokic

We give a simple and unified proof showing that the unrestricted wreath product of a weakly sofic, sofic, linear sofic, or hyperlinear group by an amenable group is weakly sofic, sofic, linear sofic, or hyperlinear, respectively. By means…

Group Theory · Mathematics 2022-02-17 Javier Brude , Román Sasyk

Using tools from the theory of optimal transport, we establish several results concerning isometric actions of amenable topological groups with potentially unbounded orbits. Specifically, suppose $d$ is a compatible left-invariant metric on…

Functional Analysis · Mathematics 2025-09-16 Christian Rosendal

Let $\Qbar$ denote the field of complex algebraic numbers. A discrete group $G$ is said to have the $\sigma$-multiplier algebraic eigenvalue property, if for every matrix $A$ with entries in the twisted group ring over the complex algebraic…

Spectral Theory · Mathematics 2007-05-23 J. Dodziuk , V. Mathai , S. Yates

This paper builds on our previous work in which we showed that, for all connected semisimple linear Lie groups $G$ acting on a non-compactly causal symmetric space $M = G/H$, every irreducible unitary representation of $G$ can be realized…

Mathematical Physics · Physics 2024-01-31 Jan Frahm , Karl-Hermann Neeb , Gestur Olafsson

An important theorem of Ling states that if $G$ is any factorizable non-fixing group of homeomorphisms of a paracompact space then its commutator subgroup $[G,G]$ is perfect. This paper is devoted to further studies on the algebraic…

Differential Geometry · Mathematics 2011-06-07 Ilona Michalik , Tomasz Rybicki

We prove that on a metrizable, compact, zero-dimensional space every free action of an amenable group is measurably isomorphic to a minimal $G$-action with the same, i.e. affinely homeomorphic, simplex of measures.

Dynamical Systems · Mathematics 2014-06-23 Bartosz Frej , Dawid Huczek

M.R.Jones and J.Wiegold in [3] have shown that if $G$ is a finite group with a subgroup $H$ of finite index $n$, then the $n$-th power of Schur multiplier of $G$, $M(G)^n$, is isomorphic to a subgroup of $M(H)$. In this paper we prove a…

Group Theory · Mathematics 2011-04-05 Mohammad Reza Rajabzadeh Moghaddam , Behrooz Mashayekhy , Saeed Kayvanfar

Uniformly finite homology is a coarse invariant for metric spaces; in particular, it is a quasi-isometry invariant for finitely generated groups. In this article, we study uniformly finite homology of finitely generated amenable groups and…

Group Theory · Mathematics 2016-01-20 Matthias Blank , Francesca Diana

In this paper we generalize the Aldous-Hoover-Kallenberg theorem concerning representations of distributions of exchangeable arrays via collections of measurable maps. We give criteria when such a representation theorem exists for arrays…

Logic · Mathematics 2021-10-12 Nathanael Ackerman

Runde and Spronk showed in 2004 that there are non-amenable groups $G$, including $\mathbb F_2$, {whose Fourier-Stieltjes algebra, $B(G)$,} is operator Connes-amenable. This result was surprising since the measure algebra $M(G)$ is…

Functional Analysis · Mathematics 2026-05-07 Volker Runde , Nico Spronk , Matthew Wiersma

We will extend earlier transference results of Neuwirth and Ricard from the context of noncommutative $L_p$-spaces associated with amenable groups to that of noncommutative $L_p$-spaces over crossed products of amenable and trace-preserving…

Functional Analysis · Mathematics 2016-11-28 A. M. González-Pérez

We prove a structure theorem for stable functions on amenable groups, which extends the arithmetic regularity lemma for stable subsets of finite groups. Given a group $G$, a function $f\colon G\to [-1,1]$ is called stable if the binary…

Logic · Mathematics 2024-06-18 Gabriel Conant , Anand Pillay