Proper actions and supported-section-valued cohomology
Abstract
Consider a proper action of $\mathbb{Z}^d$ on a smooth (perhaps non-paracompact) manifold $M$. The $p^{th}$ cohomology $H^p(\mathbb{Z}^d,\ \Gamma_{\mathrm{c}}(\mathcal{F}))$ 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 $\Phi$-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 $\Phi$, in the sense that every member of $\Phi$ has a neighborhood small with respect to the action in Palais' sense.
- Publication:
-
arXiv e-prints
- Pub Date:
- November 2024
- DOI:
- 10.48550/arXiv.2411.09857
- arXiv:
- arXiv:2411.09857
- Bibcode:
- 2024arXiv241109857C
- Keywords:
-
- Mathematics - Group Theory;
- Mathematics - Algebraic Topology;
- Mathematics - General Topology;
- Mathematics - K-Theory and Homology;
- 20J06;
- 18G40;
- 55T10;
- 54D20;
- 54D15;
- 54B15;
- 55N30;
- 18F20
- E-Print:
- 20 pages + references