English

Proper cocycles and weak forms of amenability

Group Theory 2014-09-26 v6 Operator Algebras

Abstract

Let GG and HH be locally compact, second countable groups. Assume that GG acts in a measure class preserving way on a standard probability space (X,μ)(X,\mu) such that L(X,μ)L^\infty(X,\mu) has an invariant mean and that there is a Borel cocycle α:G×XH\alpha:G\times X\rightarrow H which is proper in a suitable, natural sense. We show that if HH has one of the three properties: Haagerup property (a-T-menability), weak amenability or weak Haagerup property, then so does GG. We observe that it is the case for a weak form of measure equivalence for pairs of discrete groups.

Keywords

Cite

@article{arxiv.1403.0207,
  title  = {Proper cocycles and weak forms of amenability},
  author = {Paul Jolissaint},
  journal= {arXiv preprint arXiv:1403.0207},
  year   = {2014}
}

Comments

Presentation improved, 14 pages

R2 v1 2026-06-22T03:18:34.446Z