Volume and Euler classes in bounded cohomology of transformation groups

Fuente: arXiv
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Autores principales: Brandenbursky, Michael, Marcinkowski, Michał
Formato: Preprint
Publicado: 2023
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author Brandenbursky, Michael
Marcinkowski, Michał
author_facet Brandenbursky, Michael
Marcinkowski, Michał
contents Let $M$ be an oriented smooth manifold, and $\operatorname{Homeo}(M,ω)$ the group of measure preserving homeomorphisms of $M$, where $ω$ is a finite measure induced by a volume form. In this paper we define volume and Euler classes in bounded cohomology of an infinite dimensional transformation group $\operatorname{Homeo}_0(M,ω)$ and $\operatorname{Homeo}(M,ω)$ respectively, and in several cases prove their non-triviality. More precisely, we define: - Volume classes in $\operatorname{H}_b^n(\operatorname{Homeo}_0(M,ω))$ where $M$ is a hyperbolic manifold of dimension $n$. - Euler classes in $\operatorname{H}_b^2(\operatorname{Homeo}(S,ω))$ where $S$ is a closed hyperbolic surface. We show that Euler classes have positive norms for any closed hyperbolic $S$ and volume classes have positive norms for all hyperbolic surfaces and certain hyperbolic $3$-manifolds, and hence they are non-trivial.
format Preprint
id arxiv_https___arxiv_org_abs_2308_15974
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Volume and Euler classes in bounded cohomology of transformation groups
Brandenbursky, Michael
Marcinkowski, Michał
Geometric Topology
Dynamical Systems
Group Theory
51, 53, 55, 57K10, 58D05, 37E30
Let $M$ be an oriented smooth manifold, and $\operatorname{Homeo}(M,ω)$ the group of measure preserving homeomorphisms of $M$, where $ω$ is a finite measure induced by a volume form. In this paper we define volume and Euler classes in bounded cohomology of an infinite dimensional transformation group $\operatorname{Homeo}_0(M,ω)$ and $\operatorname{Homeo}(M,ω)$ respectively, and in several cases prove their non-triviality. More precisely, we define: - Volume classes in $\operatorname{H}_b^n(\operatorname{Homeo}_0(M,ω))$ where $M$ is a hyperbolic manifold of dimension $n$. - Euler classes in $\operatorname{H}_b^2(\operatorname{Homeo}(S,ω))$ where $S$ is a closed hyperbolic surface. We show that Euler classes have positive norms for any closed hyperbolic $S$ and volume classes have positive norms for all hyperbolic surfaces and certain hyperbolic $3$-manifolds, and hence they are non-trivial.
title Volume and Euler classes in bounded cohomology of transformation groups
topic Geometric Topology
Dynamical Systems
Group Theory
51, 53, 55, 57K10, 58D05, 37E30
url https://arxiv.org/abs/2308.15974