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We prove that amenability of a unitary co-representation $U$ of a locally compact quantum group passes to unitary co-representations that weakly contain $U$. This generalizes a result of Bekka, and answers affirmatively a question of…

Operator Algebras · Mathematics 2017-05-30 Chi-Keung Ng , Ami Viselter

We give a combinatorial characterization of amenability of monomial algebras and prove the existence of monomial Folner sequences, answering a question due to Ceccherini-Silberstein and Samet-Vaillant. We then use our characterization to…

Rings and Algebras · Mathematics 2022-11-15 Jason P. Bell , Be'eri Greenfeld

An invariant random subgroup $H \leq G$ is a random closed subgroup whose law is invariant to conjugation by all elements of $G$. When $G$ is locally compact and second countable, we show that for every invariant random subgroup $H \leq G$…

Group Theory · Mathematics 2018-04-24 Ian Biringer , Omer Tamuz

This note describes the first example of a group that is amenable, but cannot be obtained by subgroups, quotients, extensions and direct limits from the class of groups locally of subexponential growth. It has a balanced presentation…

Group Theory · Mathematics 2007-05-23 Laurent Bartholdi

We prove a new weak mean ergodic theorem (Theorem A) for 1-cocycles associated to weakly mixing representations of amenable groups. Let $G$ be a finitely generated, discrete, amenable group $G$ which admits a controlled Folner sequence. We…

Group Theory · Mathematics 2012-08-06 Ionut Chifan , Thomas Sinclair

Group classification of a class of Benjamin-Bona-Mahony (BBM) equations with time dependent coefficients is carried out. Two equivalent lists of equations possessing Lie symmetry extensions are presented: up to point equivalence within the…

Exactly Solvable and Integrable Systems · Physics 2015-06-29 Olena Vaneeva , Roman Popovych , Christodoulos Sophocleous

We consider a new group testing model wherein each item is a binary random variable defined by an a priori probability of being defective. We assume that each probability is small and that items are independent, but not necessarily…

Information Theory · Computer Science 2018-07-24 Tongxin Li , Chun Lam Chan , Wenhao Huang , Tarik Kaced , Sidharth Jaggi

Since 100 years or so, it has been usually accepted that the " conformal group " could be defined in an arbitrary dimension n as the group of transformations preserving a non degenerate flat metric up to a nonzero invertible point depending…

General Mathematics · Mathematics 2021-12-08 J. -F. Pommaret

We study rigidity properties of lattices in terms of invariant means and commensurating actions (or actions on CAT(0) cube complexes). We notably study Property FM for groups, namely that any action on a discrete set with an invariant mean…

Group Theory · Mathematics 2020-05-05 Yves Cornulier

We show an equivariant Kirchberg-Phillips-type absorption theorem for pointwise outer actions of discrete amenable groups on Kirchberg algebras with respect to natural model actions on the Cuntz algebras $\mathcal{O}_\infty$ and…

Operator Algebras · Mathematics 2018-10-04 Gabor Szabo

Banach spaces that are complemented in the second dual are characterised precisely as those spaces $X$ which enjoy the property that for every amenable semigroup $S$ there exists an $X$-valued analogue of an invariant mean defined on the…

Functional Analysis · Mathematics 2016-10-26 Tomasz Kania

In many real world problems, features do not act alone but in combination with each other. For example, in genomics, diseases might not be caused by any single mutation but require the presence of multiple mutations. Prior work on feature…

Machine Learning · Computer Science 2023-01-12 Fergus Imrie , Alexander Norcliffe , Pietro Lio , Mihaela van der Schaar

In any semigroup $S$ satisfying the Strong Folner Condition, there are three natural notions of density for a subset $A$ of $S$: Folner density $d(A)$, Banach density $d^*(A)$, and translation density $d_t(A)$. If $S$ is commutative or left…

Combinatorics · Mathematics 2025-07-23 Daniel Glasscock , Neil Hindman , Dona Strauss

We generalize Luck's Theorem to show that the L^2-Betti numbers of a residually amenable covering space are the limit of the L^2-Betti numbers of a sequence of amenable covering spaces. We show that any residually amenable covering space of…

dg-ga · Mathematics 2007-05-23 Bryan Clair

We establish a connection between two variants of van der Corput's Difference Theorem (vdCDT) for countably infinite amenable groups $G$ and the ergodic hierarchy of mixing properties of a unitary representation $U$ of $G$. In particular,…

Dynamical Systems · Mathematics 2024-10-25 Sohail Farhangi

Different notions of amenability on hypergroups and their relations are studied. Developing Leptin's theorem for discrete hypergroups, we characterize the existence of a bounded approximate identity for hypergroup Fourier algebras. We study…

Functional Analysis · Mathematics 2016-02-29 Mahmood Alaghmandan

This paper allows one to obtain a criterion for the existence of a projectively invariant measure formulated in terms of combinatorial properties of a group (amenability of some canonical quotient group). Such necessary and sufficient…

Group Theory · Mathematics 2012-11-27 Leva Beklaryan

This is an expostion of various aspects of amenability and paradoxical decompositions for groups, group actions and metric spaces. First, we review the formalism of pseudogroups, which is well adapted to stating the alternative of Tarski,…

Group Theory · Mathematics 2016-03-15 Tullio Ceccherini-Silberstein , Rostislav I. Grigorchuk , Pierre de la Harpe

Let $G$ be a second countable locally compact groupoid equipped with a Haar system $\lambda$.In this work, we introduce and develop the notion of amenability for continuous unitary representations of $G$, formulated in terms of Hilbert…

Operator Algebras · Mathematics 2026-02-13 K. N. Sridharan , N. Shravan Kumar

In this short note we introduce a new metric on certain finite groups. It leads to a class of groups for which the element orders satisfy an interesting inequality. This extends the class CP_2 studied in our previous paper [16].

Group Theory · Mathematics 2015-06-30 Marius Tărnăuceanu