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A discrete countable group \Gamma is said to be ME rigid if any discrete countable group that is measure equivalent to \Gamma is virtually isomorphic to \Gamma. In this paper, we construct ME rigid groups by amalgamating two groups…

Group Theory · Mathematics 2015-02-02 Yoshikata Kida

We show for a free action of a countable group $\Gamma$ on a finite-dimensional, compact metric space by homeomorphisms that the dynamic asymptotic dimension is either infinite or coincides with the asymptotic dimension of $\Gamma$.

Dynamical Systems · Mathematics 2025-01-07 Samantha Pilgrim

Let $\mu$ be a compactly supported probability measure on the positive half-line and let $\mu^{\boxtimes t}$ be the free multiplicative convolution semigroup. We show that the support of $\mu^{\boxtimes t}$ varies continuously as $t$…

Functional Analysis · Mathematics 2017-09-22 Xiaoxue Deng , Ping Zhong

We prove that amenability of a discrete group is equivalent to dimension flatness of certain ring inclusions naturally associated with measure preserving actions of the group. This provides a group-measure space theoretic solution to a…

Group Theory · Mathematics 2013-05-16 David Kyed , Henrik Densing Petersen

We present a detailed Hausdorff dimension analysis of the set of real numbers where the product of consecutive partial quotients in their continued fraction expansion grow at a certain rate but the growth of the single partial quotient is…

Number Theory · Mathematics 2022-08-22 Mumtaz Hussain , Bixuan Li , Nikita Shulga

We prove the dynamic asymptotic dimension of a free isometric action on a space of finite doubling dimension is either infinite or equal to the asymptotic dimension of the acting group; and give a full description of the dynamic asymptotic…

Dynamical Systems · Mathematics 2023-01-31 SJ Pilgrim

We provide a quantitative formulation of the equivalence between hyperlinearity and soficity for amenable groups, effectively showing how every hyperlinear approximation to such a group is simulated by a suitable sofic approximation. The…

Group Theory · Mathematics 2024-01-12 Peter Burton , Maksym Chaudkhari , Kate Juschenko , Kyrylo Muliarchyk

In this paper, we show that Cremona groups are sofic. We actually introduce a quantitative notion of soficity, called sofic profile, and show that the group of birational transformations of a d-dimensional variety has sofic profile at most…

Group Theory · Mathematics 2014-03-07 Yves Cornulier

Mean dimension is a topological invariant of dynamical systems, which originates with Mikhail Gromov in 1999 and which was studied with deep applications around 2000 by Elon Lindenstrauss and Benjamin Weiss within the framework of amenable…

Dynamical Systems · Mathematics 2022-11-22 Lei Jin , Yixiao Qiao

Sofic and hyperlinear groups are the countable discrete groups that can be approximated in a suitable sense by finite symmetric groups and groups of unitary matrices. These notions turned out to be very deep and fruitful, and stimulated in…

Group Theory · Mathematics 2015-05-06 Valerio Capraro , Martino Lupini

Akin's notion of good measure, introduced to classify measures on Cantor sets has been translated to dimension groups and corresponding traces by Bezuglyi and the author, but emphasizing the simple (minimal dynamical system) case. Here we…

Functional Analysis · Mathematics 2016-02-24 David Handelman

A sofic approximation to a countable group is a sequence of partial actions on finite sets that asymptotically approximates the action of the group on itself by left-translations. A group is sofic if it admits a sofic approximation. Sofic…

Dynamical Systems · Mathematics 2021-08-18 Dylan Airey , Lewis Bowen , Frank Lin

We introduce the concept of Rokhlin dimension for actions of residually compact groups on C*-algebras, which extends and unifies previous notions for actions of compact groups, residually finite groups and the reals. We then demonstrate…

Operator Algebras · Mathematics 2026-02-03 Xin Cao , Xiaochun Fang , Jianchao Wu

The asymptotic study of the conjugacy classes of a random element of the finite affine group leads one to define a probability measure on the set of all partitions of all positive integers. Four different probabilistic understandings of…

Group Theory · Mathematics 2007-05-23 Jason Fulman

The action dimension of a discrete group $G$ is the minimum dimension of contractible manifold that admits a proper $G$-action. We compute the action dimension of the direct limit of a simple complex of groups for several classes of…

Geometric Topology · Mathematics 2019-07-03 Michael W. Davis , Giang Le , Kevin Schreve

We introduce the notion of tubular dimension, and give a formula for it. As an application we show that every invariant measure of a $C^{1+\gamma}$ diffeomorphism of a closed Riemannian manifold admits an asymptotic local product structure…

Dynamical Systems · Mathematics 2024-02-13 Snir Ben Ovadia

We introduce a pointwise variant of the Assouad dimension for measures on metric spaces, and study its properties in relation to the global Assouad dimension. We show that, in general, the value of the pointwise Assouad dimension differs…

Classical Analysis and ODEs · Mathematics 2024-03-12 Roope Anttila

We construct the first examples of genuine ergodic discrete measured groupoids that are not isomorphic to any equivalence relation or transformation groupoid. We use a construction due to B.H. Neumann of an uncountable family of pairwise…

Group Theory · Mathematics 2025-10-15 Soham Chakraborty

The goal of this paper is threefold. First, we describe the notion of dissociation for closed subgroups of the group of permutations on a countably infinite set and explain its numerous consequences on unitary representations…

Group Theory · Mathematics 2026-04-28 Rémi Barritault , Colin Jahel , Matthieu Joseph

Using probabilistic methods, Collins and Dykema proved that the free product of two sofic groups amalgamated over a monotileably amenable subgroup is sofic as well. We show that the restriction is unnecessary; the free product of two sofic…

Group Theory · Mathematics 2010-11-01 Gabor Elek , Endre Szabo