Non-C*-simple groups admit non-free actions on their Poisson boundaries

Fuente: arXiv
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Autor principal: Alpeev, Andrei
Formato: Preprint
Publicado: 2024
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author Alpeev, Andrei
author_facet Alpeev, Andrei
contents It is a classical result of Kaimanovich and Vershik and independently of Rosenblatt that a non-amenable group admits a non-degenerate symmetric measure such that the Poisson boundary is trivial. Most if not all examples to date of non-free actions of countable groups on their Poisson boundaries had the stabilizers sitting inside the amenable radical. We show that every countable non-C*-simple group admits a symmetric measure of full support with non-trivial stabilizers. For a class of non-C*-simple groups with trivial amenable radical, which is non-empty as was shown by le Boudec, this gives a wealth of examples with non-normal stabilizers.
format Preprint
id arxiv_https___arxiv_org_abs_2409_02013
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Non-C*-simple groups admit non-free actions on their Poisson boundaries
Alpeev, Andrei
Group Theory
Dynamical Systems
Operator Algebras
Probability
It is a classical result of Kaimanovich and Vershik and independently of Rosenblatt that a non-amenable group admits a non-degenerate symmetric measure such that the Poisson boundary is trivial. Most if not all examples to date of non-free actions of countable groups on their Poisson boundaries had the stabilizers sitting inside the amenable radical. We show that every countable non-C*-simple group admits a symmetric measure of full support with non-trivial stabilizers. For a class of non-C*-simple groups with trivial amenable radical, which is non-empty as was shown by le Boudec, this gives a wealth of examples with non-normal stabilizers.
title Non-C*-simple groups admit non-free actions on their Poisson boundaries
topic Group Theory
Dynamical Systems
Operator Algebras
Probability
url https://arxiv.org/abs/2409.02013