Essential groupoid amenability and nuclearity of groupoid C*-algebras

Fuente: arXiv
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Main Authors: Buss, Alcides, Martínez, Diego
Format: Preprint
Published: 2025
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author Buss, Alcides
Martínez, Diego
author_facet Buss, Alcides
Martínez, Diego
contents We give an alternative construction of the essential $C^*$-algebra of an étale groupoid, along with an ``amenability'' notion for such groupoids that is implied by the nuclearity of this essential $C^*$-algebra. In order to do this we first introduce a maximal version of the essential $C^*$-algebra, and prove that every function with dense co-support can only be supported on the set of ``dangerous'' arrows. We then introduce an essential amenability condition for a groupoid, which is (strictly) weaker than its (topological) amenability. As an application, we describe the Bruce-Li algebras arising from algebraic actions of cancellative semigroups as exotic essential $C^*$-algebras.
format Preprint
id arxiv_https___arxiv_org_abs_2501_01775
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Essential groupoid amenability and nuclearity of groupoid C*-algebras
Buss, Alcides
Martínez, Diego
Operator Algebras
20L05, 46L52, 46L05
We give an alternative construction of the essential $C^*$-algebra of an étale groupoid, along with an ``amenability'' notion for such groupoids that is implied by the nuclearity of this essential $C^*$-algebra. In order to do this we first introduce a maximal version of the essential $C^*$-algebra, and prove that every function with dense co-support can only be supported on the set of ``dangerous'' arrows. We then introduce an essential amenability condition for a groupoid, which is (strictly) weaker than its (topological) amenability. As an application, we describe the Bruce-Li algebras arising from algebraic actions of cancellative semigroups as exotic essential $C^*$-algebras.
title Essential groupoid amenability and nuclearity of groupoid C*-algebras
topic Operator Algebras
20L05, 46L52, 46L05
url https://arxiv.org/abs/2501.01775