English

Cocycle superrigidity for translation actions of product groups

Dynamical Systems 2020-09-17 v1 Group Theory Operator Algebras

Abstract

Let GG be either a profinite or a connected compact group, and Γ,Λ\Gamma, \Lambda be finitely generated dense subgroups. Assuming that the left translation action of Γ\Gamma on GG is strongly ergodic, we prove that any cocycle for the left-right translation action of Γ×Λ\Gamma\times\Lambda on GG with values in a countable group is virtually cohomologous to a group homomorphism. Moreover, we prove that the same holds if GG is a (not necessarily compact) connected simple Lie group provided that Λ\Lambda contains an infinite cyclic subgroup with compact closure. We derive several applications to OE - and W^*- superrigidity. In particular, we obtain the first examples of compact actions of F2×F2\mathbb F_2\times\mathbb F_2 which are W^*-superrigid.

Keywords

Cite

@article{arxiv.1603.07616,
  title  = {Cocycle superrigidity for translation actions of product groups},
  author = {Damien Gaboriau and Adrian Ioana and Robin Tucker-Drob},
  journal= {arXiv preprint arXiv:1603.07616},
  year   = {2020}
}