Invariant $C^*$-subalgebras of the reduced group $C^*$-algebra

Fuente: arXiv
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Autori principali: Amrutam, Tattwamasi, Jiang, Yongle
Natura: Preprint
Pubblicazione: 2025
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author Amrutam, Tattwamasi
Jiang, Yongle
author_facet Amrutam, Tattwamasi
Jiang, Yongle
contents Let $Γ$ be a countable discrete group. We say that $Γ$ has $C^*$-invariant subalgebra rigidity (ISR) property if every $Γ$-invariant $C^*$-subalgebra $\mathcal{A}\le C_r^*(Γ)$ is of the form $C_r^*(N)$ for some normal subgroup $N\triangleleftΓ$. We show that all torsion-free, non-amenable (cylindrically) hyperbolic groups with property-AP and a finite direct product of such groups have this property. We also prove that an infinite group $Γ$ has the C$^*$-ISR property only if $Γ$ is simple amenable or $C^*$-simple.
format Preprint
id arxiv_https___arxiv_org_abs_2503_09548
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Invariant $C^*$-subalgebras of the reduced group $C^*$-algebra
Amrutam, Tattwamasi
Jiang, Yongle
Operator Algebras
Dynamical Systems
Functional Analysis
Let $Γ$ be a countable discrete group. We say that $Γ$ has $C^*$-invariant subalgebra rigidity (ISR) property if every $Γ$-invariant $C^*$-subalgebra $\mathcal{A}\le C_r^*(Γ)$ is of the form $C_r^*(N)$ for some normal subgroup $N\triangleleftΓ$. We show that all torsion-free, non-amenable (cylindrically) hyperbolic groups with property-AP and a finite direct product of such groups have this property. We also prove that an infinite group $Γ$ has the C$^*$-ISR property only if $Γ$ is simple amenable or $C^*$-simple.
title Invariant $C^*$-subalgebras of the reduced group $C^*$-algebra
topic Operator Algebras
Dynamical Systems
Functional Analysis
url https://arxiv.org/abs/2503.09548