English

Orbit inequivalent actions of non-amenable groups

Group Theory 2008-03-12 v2

Abstract

Consider two free measure preserving group actions Γ\actson(X,μ),Δ\actson(X,μ)\Gamma \actson (X, \mu), \Delta \actson (X, \mu), and a measure preserving action Δ\actsona(Z,ν)\Delta \actson^a (Z, \nu) where (X,μ),(Z,ν)(X, \mu), (Z, \nu) are standard probability spaces. We show how to construct free measure preserving actions Γ\actsonc(Y,m)\Gamma \actson^c (Y, m), Δ\actsond(Y,m)\Delta \actson^d (Y, m) on a standard probability space such that EΔdEΓcE_{\Delta}^d \subset E_{\Gamma}^c and dd has aa as a factor. This generalizes the standard notion of co-induction of actions of groups from actions of subgroups. We then use this construction to show that if Γ\Gamma is a countable non-amenable group, then Γ\Gamma admits continuum many orbit inequivalent free, measure preserving, ergodic actions on a standard probability space.

Keywords

Cite

@article{arxiv.0707.4215,
  title  = {Orbit inequivalent actions of non-amenable groups},
  author = {Inessa Epstein},
  journal= {arXiv preprint arXiv:0707.4215},
  year   = {2008}
}

Comments

Wrote introduction, references, etc