Intermediate subalgebras for reduced crossed products of discrete groups

Fuente: arXiv
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Autores principales: Kennedy, Matthew, Ursu, Dan
Formato: Preprint
Publicado: 2024
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author Kennedy, Matthew
Ursu, Dan
author_facet Kennedy, Matthew
Ursu, Dan
contents Let $α: Γ\curvearrowright A$ be an action of a discrete group $Γ$ on a unital C*-algebra $A$ by *-automorphisms and let $A \rtimes_{α,λ} Γ$ denote the corresponding reduced crossed product C*-algebra. Assuming that $Γ$ satisfies the approximation property, we establish a sufficient and (almost always) necessary condition on the action $α$ for the existence of a Galois correspondence between intermediate C*-algebras for the inclusion $A \subseteq A \rtimes_{α,λ} Γ$ and partial subactions of $α$. This condition, which we refer to as pointwise residual proper outerness, is a natural noncommutative generalization of freeness.
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id arxiv_https___arxiv_org_abs_2406_01546
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Intermediate subalgebras for reduced crossed products of discrete groups
Kennedy, Matthew
Ursu, Dan
Operator Algebras
Functional Analysis
Let $α: Γ\curvearrowright A$ be an action of a discrete group $Γ$ on a unital C*-algebra $A$ by *-automorphisms and let $A \rtimes_{α,λ} Γ$ denote the corresponding reduced crossed product C*-algebra. Assuming that $Γ$ satisfies the approximation property, we establish a sufficient and (almost always) necessary condition on the action $α$ for the existence of a Galois correspondence between intermediate C*-algebras for the inclusion $A \subseteq A \rtimes_{α,λ} Γ$ and partial subactions of $α$. This condition, which we refer to as pointwise residual proper outerness, is a natural noncommutative generalization of freeness.
title Intermediate subalgebras for reduced crossed products of discrete groups
topic Operator Algebras
Functional Analysis
url https://arxiv.org/abs/2406.01546