Noncommutative topological boundaries and amenable invariant random intermediate subalgebras

Fuente: arXiv
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Autore principale: Zhou, Shuoxing
Natura: Preprint
Pubblicazione: 2024
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author Zhou, Shuoxing
author_facet Zhou, Shuoxing
contents As an analogue of the topological boundary of discrete groups $Γ$, we define the noncommutative topological boundary of tracial von Neumann algebras $(M, τ)$ and apply it to generalize the main results of [AHO23], showing that for a trace-preserving action $Γ\curvearrowright (A, τ_A)$ on an amenable tracial von Neumann algebra, any $Γ$-invariant amenable intermediate subalgebra between $A$ and $Γ\ltimes A$ is necessarily a subalgebra of $\mathrm{Rad}(Γ) \ltimes A$. By taking $(A, τ_A) = L^\infty(X, ν_X)$ for a free pmp action $Γ\curvearrowright (X, ν_X)$, we obtain a similar result for the invariant subequivalence relations of $\mathcal{R}_{Γ\curvearrowright X}$.
format Preprint
id arxiv_https___arxiv_org_abs_2407_10905
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Noncommutative topological boundaries and amenable invariant random intermediate subalgebras
Zhou, Shuoxing
Operator Algebras
Dynamical Systems
Group Theory
As an analogue of the topological boundary of discrete groups $Γ$, we define the noncommutative topological boundary of tracial von Neumann algebras $(M, τ)$ and apply it to generalize the main results of [AHO23], showing that for a trace-preserving action $Γ\curvearrowright (A, τ_A)$ on an amenable tracial von Neumann algebra, any $Γ$-invariant amenable intermediate subalgebra between $A$ and $Γ\ltimes A$ is necessarily a subalgebra of $\mathrm{Rad}(Γ) \ltimes A$. By taking $(A, τ_A) = L^\infty(X, ν_X)$ for a free pmp action $Γ\curvearrowright (X, ν_X)$, we obtain a similar result for the invariant subequivalence relations of $\mathcal{R}_{Γ\curvearrowright X}$.
title Noncommutative topological boundaries and amenable invariant random intermediate subalgebras
topic Operator Algebras
Dynamical Systems
Group Theory
url https://arxiv.org/abs/2407.10905