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Main Author: Palmstrøm, Mathias
Format: Preprint
Published: 2023
Subjects:
Online Access:https://arxiv.org/abs/2311.12428
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author Palmstrøm, Mathias
author_facet Palmstrøm, Mathias
contents We generalize the ideal completions of countable discrete groups, as introduced by Brown and Guentner, to second countable Hausdorff étale groupoids. Specifically, to every pair consisting of an algebraic ideal in the algebra of bounded Borel functions on the groupoid and a non-empty family of quasi-invariant measures on the unit space, we construct a $\rm C^*$-algebra in a way which naturally encapsulates the constructions of the full and reduced groupoid $\rm C^*$-algebras. We investigate the connection between these constructions and the Haagerup property, and use the construction to show the existence of many exotic groupoid $\rm C^*$-algebras for certain classes of groupoids.
format Preprint
id arxiv_https___arxiv_org_abs_2311_12428
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Exotic $\rm C^*$-completions of étale groupoids
Palmstrøm, Mathias
Operator Algebras
46L05, 46L55, 22A22
We generalize the ideal completions of countable discrete groups, as introduced by Brown and Guentner, to second countable Hausdorff étale groupoids. Specifically, to every pair consisting of an algebraic ideal in the algebra of bounded Borel functions on the groupoid and a non-empty family of quasi-invariant measures on the unit space, we construct a $\rm C^*$-algebra in a way which naturally encapsulates the constructions of the full and reduced groupoid $\rm C^*$-algebras. We investigate the connection between these constructions and the Haagerup property, and use the construction to show the existence of many exotic groupoid $\rm C^*$-algebras for certain classes of groupoids.
title Exotic $\rm C^*$-completions of étale groupoids
topic Operator Algebras
46L05, 46L55, 22A22
url https://arxiv.org/abs/2311.12428