On the Betti Numbers of Finite Volume Hyperbolic Manifolds

Fuente: arXiv
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Autori principali: Di Cerbo, Luca F., Stern, Mark
Natura: Preprint
Pubblicazione: 2020
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author Di Cerbo, Luca F.
Stern, Mark
author_facet Di Cerbo, Luca F.
Stern, Mark
contents We obtain strong upper bounds for the Betti numbers of compact complex-hyperbolic manifolds. We use the unitary holonomy to improve the results given by the most direct application of the techniques of [DS17]. We also provide effective upper bounds for Betti numbers of compact quaternionic- and Cayley-hyperbolic manifolds in most degrees. More importantly, we extend our techniques to complete finite volume real- and complex-hyperbolic manifolds. In this setting, we develop new monotonicity inequalities for strongly harmonic forms on hyperbolic cusps and employ a new peaking argument to estimate $L^2$-cohomology ranks. Finally, we provide bounds on the de Rham cohomology of such spaces, using a combination of our bounds on $L^2$-cohomology, bounds on the number of cusps in terms of the volume, and the topological interpretation of reduced $L^2$-cohomology on certain rank one locally symmetric spaces.
format Preprint
id arxiv_https___arxiv_org_abs_2009_11431
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle On the Betti Numbers of Finite Volume Hyperbolic Manifolds
Di Cerbo, Luca F.
Stern, Mark
Differential Geometry
Geometric Topology
We obtain strong upper bounds for the Betti numbers of compact complex-hyperbolic manifolds. We use the unitary holonomy to improve the results given by the most direct application of the techniques of [DS17]. We also provide effective upper bounds for Betti numbers of compact quaternionic- and Cayley-hyperbolic manifolds in most degrees. More importantly, we extend our techniques to complete finite volume real- and complex-hyperbolic manifolds. In this setting, we develop new monotonicity inequalities for strongly harmonic forms on hyperbolic cusps and employ a new peaking argument to estimate $L^2$-cohomology ranks. Finally, we provide bounds on the de Rham cohomology of such spaces, using a combination of our bounds on $L^2$-cohomology, bounds on the number of cusps in terms of the volume, and the topological interpretation of reduced $L^2$-cohomology on certain rank one locally symmetric spaces.
title On the Betti Numbers of Finite Volume Hyperbolic Manifolds
topic Differential Geometry
Geometric Topology
url https://arxiv.org/abs/2009.11431