English

OE and W* superrigidity results for actions by surface braid groups

Operator Algebras 2017-05-23 v2 Dynamical Systems Group Theory

Abstract

We show that several important normal subgroups Γ\Gamma of the mapping class group of a surface satisfy the following property: any free, ergodic, probability measure preserving action ΓX\Gamma \curvearrowright X is stably OE-superrigid. These include the central quotients of most surface braid groups and most Torelli groups and Johnson kernels. In addition, we show that all these groups satisfy the measure equivalence rigidity and we describe all their lattice-embeddings. Using these results in combination with previous results from [CIK13] we deduce that any free, ergodic, probability measure preserving action of almost any surface braid group is stably W*-superrigid, i.e., it can be completely reconstructed from its von Neumann algebra.

Keywords

Cite

@article{arxiv.1502.02391,
  title  = {OE and W* superrigidity results for actions by surface braid groups},
  author = {Ionut Chifan and Yoshikata Kida},
  journal= {arXiv preprint arXiv:1502.02391},
  year   = {2017}
}

Comments

44 pages, 2 figures

R2 v1 2026-06-22T08:25:13.377Z