# Actions of F infty whose II 1 factors and orbit equivalence relations have prescribed fundamental group - Mathematics > Operator Algebras

Actions of F infty whose II 1 factors and orbit equivalence relations have prescribed fundamental group - Mathematics > Operator Algebras - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: We show that given any subgroup F of R + which is either countable or belongsto a certain -large- class of uncountable subgroups, there exist continuouslymany free ergodic probability measure preserving actions \sigma i of the freegroup with infinitely many generators such that their associated group measurespace II 1 factors M i and orbit equivalence relations R i have fundamentalgroup equal to F and with M i respectively R i stably non-isomorphic.Moreover, these actions can be taken so that R i has no outer automorphisms andany automorphism of M i is unitary conjugate to an automorphism that actstrivially on $L^\inftyX i \subset M i$.

Autor: Sorin Popa, Stefaan Vaes

Fuente: https://arxiv.org/