English

Cocycle superrigidity for profinite actions of irreducible lattices

Dynamical Systems 2021-04-07 v2 Group Theory Operator Algebras

Abstract

Let Γ\Gamma be an irreducible lattice in a product of two locally compact groups and assume that Γ\Gamma is densely embedded in a profinite group KK. We give necessary conditions which imply that the left translation action ΓK\Gamma\curvearrowright K is "virtually" cocycle superrigid: any cocycle w:Γ×KΔw:\Gamma\times K\rightarrow\Delta with values in a countable group Δ\Delta is cohomologous to a cocycle which factors through the map Γ×KΓ×K0\Gamma\times K\rightarrow\Gamma\times K_0, for some finite quotient group K0K_0 of KK. As a corollary, we deduce that any ergodic profinite action of Γ=SL2(Z[S1])\Gamma=\text{SL}_2(\mathbb Z[S^{-1}]) is virtually cocycle superrigid and virtually W^*-superrigid, for any finite nonempty set of primes SS.

Keywords

Cite

@article{arxiv.1910.08642,
  title  = {Cocycle superrigidity for profinite actions of irreducible lattices},
  author = {Daniel Drimbe and Adrian Ioana and Jesse Peterson},
  journal= {arXiv preprint arXiv:1910.08642},
  year   = {2021}
}