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In previous work, I introduced a measure-conjugacy invariant for sofic group actions called sofic entropy. Here it is proven that the sofic entropy of an amenable group action equals its classical entropy. The proof uses a new…

Dynamical Systems · Mathematics 2011-03-29 Lewis Bowen

Associated to any orthogonal representation of a countable discrete group is an probability measure-preserving action called the Gaussian action. Using the Polish model formalism we developed before, we compute the entropy (in the sense of…

Dynamical Systems · Mathematics 2016-05-17 Ben Hayes

Let $G$ be a countable discrete amenable group which acts continuously on a compact metric space $X$ and let $\mu$ be an ergodic $G-$invariant Borel probability measure on $X$. For a fixed tempered F{\o}lner sequence $\{F_n\}$ in $G$ with…

Dynamical Systems · Mathematics 2017-08-08 Dongmei Zheng , Ercai Chen

Ergodic theory includes several notions of entropy for probability-preserving actions of countable groups. These include Kolmogorov--Sinai entropy based on F\o lner sequences for amenable groups, entropy defined using a random ordering of…

Operator Algebras · Mathematics 2026-03-23 Tim Austin

Let $G$ and $H$ be infinite finitely generated amenable groups. This paper studies two notions of equivalence between actions of such groups on standard Borel probability spaces. They are defined as stable orbit equivalences in which the…

Dynamical Systems · Mathematics 2016-11-08 Tim Austin

In this paper, we introduce a new entropy-like invariant, named Hausdorff metric entropy, for finitely generated semigroups acting on compact metric spaces from a set-valued view and study its properties. We establish the relation between…

Dynamical Systems · Mathematics 2016-01-14 Bingzhe Hou , Xu Wang

In this paper, entropies, including measure-theoretic entropy and topological entropy, are considered for random $\mathbb{Z}^k$-actions which are generated by random compositions of the generators of $\mathbb{Z}^k$-actions. Applying Pesin's…

Dynamical Systems · Mathematics 2017-01-04 Yujun Zhu

The main purpose of this article is to provide a common generalization of the notions of a topological and Kolmogorov-Sinai entropy for arbitrary representations of discrete amenable groups on objects of (abstract) categories. This is…

Dynamical Systems · Mathematics 2015-10-14 Nikita Moriakov

Entropy of measure preserving or continuous actions of amenable discrete groups allows for various equivalent approaches. Among them are the ones given by the techniques developed by Ollagnier and Pinchon on the one hand and the…

Dynamical Systems · Mathematics 2025-04-09 Till Hauser , Friedrich Martin Schneider

Classical ergodic theory for integer-group actions uses entropy as a complete invariant for isomorphism of IID (independent, identically distributed) processes (a.k.a. product measures). This theory holds for amenable groups as well.…

Dynamical Systems · Mathematics 2018-09-10 Russell Lyons

Bowen's notion of sofic entropy is a powerful invariant for classifying probability-preserving actions of sofic groups. It can be defined in terms of the covering numbers of certain metric spaces associated to such an action, the `model…

Dynamical Systems · Mathematics 2016-06-07 Tim Austin

We continue the study of Rokhlin entropy, an isomorphism invariant for probability-measure-preserving actions of countable groups introduced in Part I. In this paper we prove a non-ergodic finite generator theorem and use it to establish…

Dynamical Systems · Mathematics 2020-02-25 Andrei Alpeev , Brandon Seward

We develop a fine-scale local analysis of measure entropy and measure sequence entropy based on combinatorial independence. The concepts of measure IE-tuples and measure IN-tuples are introduced and studied in analogy with their…

Dynamical Systems · Mathematics 2007-05-24 David Kerr , Hanfeng Li

In this paper, we introduce the notions of topological pressure and measure-theoretic entropy for a free semigroup action. Suppose that a free semigroup acts on a compact metric space by continuous self-maps. To this action, we assign a…

Dynamical Systems · Mathematics 2016-10-27 Xiaogang Lin , Dongkui Ma , Yupan Wang

In this short note, for countably infinite amenable group actions, we provide topological proofs for the following results: Bowen topological entropy (dimensional entropy) of the whole space equals the usual topological entropy along…

Dynamical Systems · Mathematics 2017-12-19 Dou Dou , Ruifeng Zhang

We investigate the connections between independence, sequence entropy, and mean sensitivity for a measure preserving system under the action of a countable infinite discrete group. We establish that every sequence entropy tuple for an…

Dynamical Systems · Mathematics 2025-04-03 Chunlin Liu , Leiye Xu , Shuhao Zhang

We generalize the notion of isoperimetric profiles of finitely generated groups to their actions by measuring the boundary of finite subgraphings of the orbit graphing. We prove that like the classical isoperimetric profiles for groups,…

Dynamical Systems · Mathematics 2023-10-05 Zihan Xia

In this short note we study the entropy for algebraic actions of certain amenable groups. The possible values for this entropy are studied. Various fundamental results about certain classes of amenable groups are reproved using elementary…

Dynamical Systems · Mathematics 2013-03-15 Nhan-Phu Chung , Andreas Thom

We prove that for a measure preserving action of a sofic group with positive sofic entropy, the set of points with finite stabilizer have positive measure. This extends results of Weiss and Seward for amenable groups and free groups,…

Dynamical Systems · Mathematics 2016-08-24 Tom Meyerovitch

For actions of a sofic group on probability spaces, the entropy has been defined by Bowen, with an extension by Kerr-Li. In particular, when the action is by homeomorphisms of a compact space preserving a given measure, Kerr-Li show one can…

Dynamical Systems · Mathematics 2016-05-17 Ben Hayes