Rigid sides of approximately finite dimensional simple operator algebras in non-separable category

Abstract

Applying Popa's orthogonality method to a new class of groups, we construct amenable group factors which are prime and have no infinite dimensional regular abelian *-subalgebras. By adjusting Farah--Katsura's solution of Dixmier's problem to the von Neumann algebra setting, we obtain the first examples of prime AFD factors and tensorially prime simple AF-algebras. Our results are proved in ZFC, thus in particular answering questions asked by Farah--Hathaway--Katsura--Tikuisis. We also directly determine central sequences of certain crossed products. This concludes the failure of the Kirchberg ${\mathcal{O}}_{\infty }$-absorption theorem in the non-separable setting.

Minor revision, added some explanations, to appear in IMRN, 19 pages