English

Bounded Cohomology of Groups acting on Cantor sets

Group Theory 2022-10-04 v1

Abstract

We study the bounded cohomology of certain groups acting on the Cantor set. More specifically, we consider the full group of homeomorphisms of the Cantor set as well as Thompson's group VV. We prove that both of these groups are boundedly acyclic, that is the bounded cohomology with trivial real coefficients vanishes in positive degrees. Combining this result with the already established Z\mathbb{Z}-acyclicity of Thompson's group VV, will make VV the first example of a finitely generated group, in fact the first example of a group of type FF_\infty, which is universally boundedly acyclic. Before proving bounded acyclicity, we gather various properties of the groups under consideration and certain subgroups thereof. As a consequence the proofs of bounded acyclicity will be relatively short. It will turn out that the approaches to handle these groups are very similar. This suggests that there could be a unifying approach which would imply the bounded acyclicity of a larger class of groups acting on the Cantor set, including the discussed ones.

Keywords

Cite

@article{arxiv.2210.00459,
  title  = {Bounded Cohomology of Groups acting on Cantor sets},
  author = {Konstantin Andritsch},
  journal= {arXiv preprint arXiv:2210.00459},
  year   = {2022}
}