English

A unique Cartan subalgebra result for Bernoulli actions of weakly amenable groups

Operator Algebras 2024-04-15 v1 Group Theory

Abstract

We show that if Γ(XΓ,μΓ)\Gamma\curvearrowright (X^\Gamma,\mu^\Gamma) is a Bernoulli action of an i.c.c. nonamenable group Γ\Gamma which is weakly amenable with Cowling-Haagerup constant 11, and Λ(Y,ν)\Lambda\curvearrowright(Y,\nu) is a free ergodic p.m.p. algebraic action of a group Λ\Lambda, then the isomorphism L(XΓ)ΓL(Y)ΛL^\infty(X^\Gamma)\rtimes\Gamma\cong L^\infty(Y)\rtimes\Lambda implies that L(XΓ)L^\infty(X^\Gamma) and L(Y)L^\infty(Y) are unitarily conjugate. This is obtained by showing a new rigidity result of non properly proximal groups and combining it with a rigidity result of properly proximal groups from \cite{BIP21}.

Keywords

Cite

@article{arxiv.2404.08182,
  title  = {A unique Cartan subalgebra result for Bernoulli actions of weakly amenable groups},
  author = {Changying Ding},
  journal= {arXiv preprint arXiv:2404.08182},
  year   = {2024}
}