TY - JOUR
T1 - Volume and Euler classes in bounded cohomology of transformation groups
AU - Brandenbursky, Michael
AU - Marcinkowski, Michał
N1 - Publisher Copyright: © 2024 Cambridge University Press. All rights reserved.
PY - 2024/1/1
Y1 - 2024/1/1
N2 - Let M be an oriented smooth manifold and 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 Homeo0(M, ω) and Homeo+(M, ω), respectively, and in several cases prove their non-triviality. More precisely, we define: • Volume classes in Hnb ( Homeo0(M, ω)), where M is a hyperbolic manifold of dimension n. • Euler classes in H2b ( Homeo+ (S, ω)), where S is an oriented closed hyperbolic surface. We show that Euler classes have positive norms for any closed hyperbolic surface and volume classes have positive norms for all hyperbolic surfaces and certain hyperbolic 3-manifolds; hence, they are non-trivial.
AB - Let M be an oriented smooth manifold and 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 Homeo0(M, ω) and Homeo+(M, ω), respectively, and in several cases prove their non-triviality. More precisely, we define: • Volume classes in Hnb ( Homeo0(M, ω)), where M is a hyperbolic manifold of dimension n. • Euler classes in H2b ( Homeo+ (S, ω)), where S is an oriented closed hyperbolic surface. We show that Euler classes have positive norms for any closed hyperbolic surface and volume classes have positive norms for all hyperbolic surfaces and certain hyperbolic 3-manifolds; hence, they are non-trivial.
KW - bounded cohomology
KW - characteristic classes
KW - euler class
KW - homeomomorphisms of manifolds
KW - mapping class group
KW - volume class
UR - http://www.scopus.com/inward/record.url?scp=85206251793&partnerID=8YFLogxK
U2 - https://doi.org/10.1017/S0017089524000223
DO - https://doi.org/10.1017/S0017089524000223
M3 - Article
SN - 0017-0895
JO - Glasgow Mathematical Journal
JF - Glasgow Mathematical Journal
ER -