Strongly Singular Masas in Type $I{I}_1$ Factors

Abstract

In this paper we introduce and study strongly singular maximal abelian self-adjoint subalgebras of type $I{I}_1$ factors. We show that certain elements of free groups and of non-elementary hyperbolic groups generate such masas, and these also give new examples of masas for which Popa's invariant delta is 1. We also explore the connection between Popa's invariant and strong singularity.

22 pages, latex file, Geom. and Funct. Anal, to appear

Cited by in corpus (6)

• Ergodic theory and maximal abelian subalgebras of the hyperfinite factor
• Mixing subalgebras of finite von Neumann algebras
• Weak mixing for locally compact quantum groups
• Strong Singularity for Subfactors
• Values of the Pukanszky invariant in free group factors and the hyperfinite factor
• Unitary perturbations of masas in type $I{I}_1$ factors