Nuclear dimension of groupoid C*-algebras with large abelian isotropy, with applications to C*-algebras of directed graphs and twists

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Main Authors: Huef, Astrid an, Williams, Dana P.
Format: Preprint
Published: 2024
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author Huef, Astrid an
Williams, Dana P.
author_facet Huef, Astrid an
Williams, Dana P.
contents We characterise when the C*-algebra C*(G) of a locally compact and Hausdorff groupoid G is subhomogeneous, that is, when its irreducible representations have bounded finite dimension; if so we establish a bound for its nuclear dimension in terms of the topological dimensions of the unit space of the groupoid and the spectra of the primitive ideal spaces of the isotropy subgroups. For an etale groupoid G, we also establish a bound on the nuclear dimension of its C*-algebra provided the quotient of G by its isotropy subgroupid has finite dynamic asymptotic dimension in the sense of Guentner, Willet and Yu. Our results generalise those of C. Böncicke and K. Li to groupoids with large isotropy, including graph groupoids of directed graphs. We find that all graph C*-algebras that are stably finite have nuclear dimension at most 1. We also show that the nuclear dimension of the C*-algebra of a twist over G has the same bound on the nuclear dimension as for C*(G) and the twisted groupoid C*-algebra.
format Preprint
id arxiv_https___arxiv_org_abs_2412_10241
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Nuclear dimension of groupoid C*-algebras with large abelian isotropy, with applications to C*-algebras of directed graphs and twists
Huef, Astrid an
Williams, Dana P.
Operator Algebras
46L05, 22A22
We characterise when the C*-algebra C*(G) of a locally compact and Hausdorff groupoid G is subhomogeneous, that is, when its irreducible representations have bounded finite dimension; if so we establish a bound for its nuclear dimension in terms of the topological dimensions of the unit space of the groupoid and the spectra of the primitive ideal spaces of the isotropy subgroups. For an etale groupoid G, we also establish a bound on the nuclear dimension of its C*-algebra provided the quotient of G by its isotropy subgroupid has finite dynamic asymptotic dimension in the sense of Guentner, Willet and Yu. Our results generalise those of C. Böncicke and K. Li to groupoids with large isotropy, including graph groupoids of directed graphs. We find that all graph C*-algebras that are stably finite have nuclear dimension at most 1. We also show that the nuclear dimension of the C*-algebra of a twist over G has the same bound on the nuclear dimension as for C*(G) and the twisted groupoid C*-algebra.
title Nuclear dimension of groupoid C*-algebras with large abelian isotropy, with applications to C*-algebras of directed graphs and twists
topic Operator Algebras
46L05, 22A22
url https://arxiv.org/abs/2412.10241