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Hauptverfasser: Farsi, Carla, Proctor, Emily, Seaton, Christopher
Format: Preprint
Veröffentlicht: 2023
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Online-Zugang:https://arxiv.org/abs/2310.12073
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author Farsi, Carla
Proctor, Emily
Seaton, Christopher
author_facet Farsi, Carla
Proctor, Emily
Seaton, Christopher
contents We introduce the universal Euler characteristic of orbit space definable groupoids, a class of groupoids containing cocompact proper Lie groupoids as well as translation groupoids associated to proper definable group actions. We show that every additive and multiplicative invariant of orbit space definable groupoids with an additional local triviality hypothesis arises as a ring homomorphism applied to the universal Euler characteristic. This in particular includes the $Γ$-orbifold Euler characteristic introduced by the first and third authors when $Γ$ is a finitely presented group. For definable groupoids, where the object and arrow spaces as well as the structure maps are definable, we also introduce a Burnside group (which admits a partial multiplication), which generalizes the classical Burnside ring associated to compact Lie groups.
format Preprint
id arxiv_https___arxiv_org_abs_2310_12073
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The universal Euler characteristic and Burnside group for definable groupoids
Farsi, Carla
Proctor, Emily
Seaton, Christopher
Differential Geometry
Algebraic Topology
22A22, 14P10, 19A22, 58H05
We introduce the universal Euler characteristic of orbit space definable groupoids, a class of groupoids containing cocompact proper Lie groupoids as well as translation groupoids associated to proper definable group actions. We show that every additive and multiplicative invariant of orbit space definable groupoids with an additional local triviality hypothesis arises as a ring homomorphism applied to the universal Euler characteristic. This in particular includes the $Γ$-orbifold Euler characteristic introduced by the first and third authors when $Γ$ is a finitely presented group. For definable groupoids, where the object and arrow spaces as well as the structure maps are definable, we also introduce a Burnside group (which admits a partial multiplication), which generalizes the classical Burnside ring associated to compact Lie groups.
title The universal Euler characteristic and Burnside group for definable groupoids
topic Differential Geometry
Algebraic Topology
22A22, 14P10, 19A22, 58H05
url https://arxiv.org/abs/2310.12073