Compressible subalgebras in II$_1$ factors
Operator Algebras
2025-10-21 v1
Abstract
Given a II factor , a W-subalgebra is {\it compressible} if for any there exists a finite set of unitary elements such that , , . Any W-subalgebra in a II factor which admits a diffuse W-algebra that's free independent to , is compressible in . We prove that if is compressible, then contains a copy of the coarse bimodule for any AFD subalgebra . We use this result to provide examples of inclusions of factors that are ergodic but not AFD-ergodic, even after stabilizing by .
Cite
@article{arxiv.2510.17076,
title = {Compressible subalgebras in II$_1$ factors},
author = {Sorin Popa},
journal= {arXiv preprint arXiv:2510.17076},
year = {2025}
}
Comments
21 pages