On finite index subfactors of super McDuff II_1 factors

Abstract

A II1 factor M has the super McDuff property if the central sequence algebra
M′ ∩ M^U is a II1 factor. Suppose that N ⊂ M be an inclusion of II1 factors with finite
Jones index. In this note we prove that N has the super McDuff property if and only if M
has the super McDuff property. We prove also that the same permanence result holds in
the case of the uniform super McDuff property introduced recently. This answers a
question posed by I. Goldbring.