A non-amenable groupoid whose maximal and reduced C^*-algebras are the same

2015/04/21 by Rufus Willett, Willett, Rufus · 7 citations
Mathematics · #22A22 #43A07 #46L85 #Advanced Banach Space Theory #Advanced Operator Algebra Research #Advanced Topics in Algebra #FOS: Mathematics #Operator Algebras (math.OA)

paper · pdf · doi:10.48550/arxiv.1504.05615

openalex publication_date 2015/04/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We construct a locally compact groupoid with the properties in the title. Our example is based closely on constructions used by Higson, Lafforgue, and Skandalis in their work on counterexamples to the Baum-Connes conjecture. It is a bundle of countable groups over the one point compactification of the natural numbers, and is Hausdorff, second countable and étale.

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• Asymptotic expansion for groupoids and Roe type algebras

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