Categorical approach to the Baum-Connes conjecture for étale groupoids

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Hauptverfasser: Bönicke, Christian, Proietti, Valerio
Format: Preprint
Veröffentlicht: 2022
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author Bönicke, Christian
Proietti, Valerio
author_facet Bönicke, Christian
Proietti, Valerio
contents We consider the equivariant Kasparov category associated to an étale groupoid, and by leveraging its triangulated structure we study its localization at the "weakly contractible" objects, extending previous work by R. Meyer and R. Nest. We prove the subcategory of weakly contractible objects is complementary to the localizing subcategory of projective objects, which are defined in terms of "compactly induced" algebras with respect to certain proper subgroupoids related to isotropy. The resulting "strong" Baum-Connes conjecture implies the classical one, and its formulation clarifies several permanence properties and other functorial statements. We present multiple applications, including consequences for the Universal Coefficient Theorem, a generalized "Going-Down" principle, injectivity results for groupoids that are amenable at infinity, the Baum-Connes conjecture for group bundles, and a result about the invariance of $K$-groups of twisted groupoid $C^*$-algebras under homotopy of twists.
format Preprint
id arxiv_https___arxiv_org_abs_2202_08067
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Categorical approach to the Baum-Connes conjecture for étale groupoids
Bönicke, Christian
Proietti, Valerio
K-Theory and Homology
Category Theory
Operator Algebras
19K35, 46L80, 18G80
We consider the equivariant Kasparov category associated to an étale groupoid, and by leveraging its triangulated structure we study its localization at the "weakly contractible" objects, extending previous work by R. Meyer and R. Nest. We prove the subcategory of weakly contractible objects is complementary to the localizing subcategory of projective objects, which are defined in terms of "compactly induced" algebras with respect to certain proper subgroupoids related to isotropy. The resulting "strong" Baum-Connes conjecture implies the classical one, and its formulation clarifies several permanence properties and other functorial statements. We present multiple applications, including consequences for the Universal Coefficient Theorem, a generalized "Going-Down" principle, injectivity results for groupoids that are amenable at infinity, the Baum-Connes conjecture for group bundles, and a result about the invariance of $K$-groups of twisted groupoid $C^*$-algebras under homotopy of twists.
title Categorical approach to the Baum-Connes conjecture for étale groupoids
topic K-Theory and Homology
Category Theory
Operator Algebras
19K35, 46L80, 18G80
url https://arxiv.org/abs/2202.08067