On the structural theory of $\mathrm{I}{\mathrm{I}}_1$ factors of negatively curved groups

Abstract

Ozawa showed that for any i.c.c., hyperbolic group, the associated group factor is solid. Developing a new approach that combines some methods of Peterson, Ozawa and Popa, and Ozawa, we strengthen this result by showing that these factors are strongly solid. Using our methods in cooperation with a cocycle superrigidity result of Ioana, we show that profinite actions of lattices in Sp(n,1), n>1, are virtually W*-superrigid.

arXiv commentFina version; to appear as such in Annales Scientifiques de l'ENS