Coamenability and strong ergodicity

Fuente: arXiv
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Main Author: Hayes, Ben
Format: Preprint
Published: 2026
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author Hayes, Ben
author_facet Hayes, Ben
contents Following methods of Bannon-Marrakchi-Ozawa, we show that for coamenable inclusion $\mathcal{S}\leq \mathcal{R}$ of ergodic, probability measure-preserving relations, we have that $\mathcal{R}$ is strongly ergodic if and only if $\mathcal{S}$ is strongly ergodic. More general results are given when $\mathcal{S}\leq \mathcal{R}$ is coamenable, $\mathcal{R}$ is strongly ergodic, but we do not assume ergodicity of $\mathcal{S}$. As a consequence, if $Λ\leq Γ$ is a coamenable inclusion of groups, then any strongly ergodic $Γ$ action has countably many ergodic components for the $Λ$ action, each of which is strongly ergodic.
format Preprint
id arxiv_https___arxiv_org_abs_2605_18433
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Coamenability and strong ergodicity
Hayes, Ben
Dynamical Systems
Group Theory
Operator Algebras
Following methods of Bannon-Marrakchi-Ozawa, we show that for coamenable inclusion $\mathcal{S}\leq \mathcal{R}$ of ergodic, probability measure-preserving relations, we have that $\mathcal{R}$ is strongly ergodic if and only if $\mathcal{S}$ is strongly ergodic. More general results are given when $\mathcal{S}\leq \mathcal{R}$ is coamenable, $\mathcal{R}$ is strongly ergodic, but we do not assume ergodicity of $\mathcal{S}$. As a consequence, if $Λ\leq Γ$ is a coamenable inclusion of groups, then any strongly ergodic $Γ$ action has countably many ergodic components for the $Λ$ action, each of which is strongly ergodic.
title Coamenability and strong ergodicity
topic Dynamical Systems
Group Theory
Operator Algebras
url https://arxiv.org/abs/2605.18433