Proper actions and supported-section-valued cohomology

Fuente: arXiv
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Main Author: Chirvasitu, Alexandru
Format: Preprint
Published: 2024
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author Chirvasitu, Alexandru
author_facet Chirvasitu, Alexandru
contents Consider a proper action of $\mathbb{Z}^d$ on a smooth (perhaps non-paracompact) manifold $M$. The $p^{th}$ cohomology $H^p(\mathbb{Z}^d,\ Γ_{\mathrm{c}}(\mathcal{F}))$ valued in the space of compactly-supported sections of a natural sheaf $\mathcal{F}$ on $M$ (such as those of smooth function germs, smooth $k$-form germs, etc.) vanishes for $p\ne d$ (the cohomological dimension of $\mathbb{Z}^d$) and, at $d$, equals the space of compactly-supported sections of the descent ($\mathbb{G}$-invariant push-forward) $\mathcal{F}/\mathbb{Z}^d$ to the orbifold quotient $M/\mathbb{Z}^d$. We prove this and analogous results on $\mathbb{Z}^d$ cohomology valued in $Φ$-supported sections of an equivariant appropriately soft sheaf $\mathcal{F}$ in a broader context of $\mathbb{Z}^d$-actions proper with respect to a paracompactifying family of supports $Φ$, in the sense that every member of $Φ$ has a neighborhood small with respect to the action in Palais' sense.
format Preprint
id arxiv_https___arxiv_org_abs_2411_09857
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Proper actions and supported-section-valued cohomology
Chirvasitu, Alexandru
Group Theory
Algebraic Topology
General Topology
K-Theory and Homology
20J06, 18G40, 55T10, 54D20, 54D15, 54B15, 55N30, 18F20
Consider a proper action of $\mathbb{Z}^d$ on a smooth (perhaps non-paracompact) manifold $M$. The $p^{th}$ cohomology $H^p(\mathbb{Z}^d,\ Γ_{\mathrm{c}}(\mathcal{F}))$ valued in the space of compactly-supported sections of a natural sheaf $\mathcal{F}$ on $M$ (such as those of smooth function germs, smooth $k$-form germs, etc.) vanishes for $p\ne d$ (the cohomological dimension of $\mathbb{Z}^d$) and, at $d$, equals the space of compactly-supported sections of the descent ($\mathbb{G}$-invariant push-forward) $\mathcal{F}/\mathbb{Z}^d$ to the orbifold quotient $M/\mathbb{Z}^d$. We prove this and analogous results on $\mathbb{Z}^d$ cohomology valued in $Φ$-supported sections of an equivariant appropriately soft sheaf $\mathcal{F}$ in a broader context of $\mathbb{Z}^d$-actions proper with respect to a paracompactifying family of supports $Φ$, in the sense that every member of $Φ$ has a neighborhood small with respect to the action in Palais' sense.
title Proper actions and supported-section-valued cohomology
topic Group Theory
Algebraic Topology
General Topology
K-Theory and Homology
20J06, 18G40, 55T10, 54D20, 54D15, 54B15, 55N30, 18F20
url https://arxiv.org/abs/2411.09857