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arXiv · 1612.09569

Mixing and weakly mixing abelian subalgebras of type II$_1$ factors

Jan Cameron·Junsheng Fang·Kunal Mukherjee
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Abstract

This paper studies weakly mixing (singular) and mixing masas in type $\rm{II}_{1}$ factors from a bimodule point of view. Several necessary and sufficient conditions to characterize the normalizing algebra of a masa are presented. We also study the structure of mixing inclusions, with special attention paid to masas of product class. A recent result of Jolissaint and Stalder concerning mixing masas arising out of inclusions of groups is revisited. One consequence of our structural results rules out the existence of certain Koopman-realizable measures, arising from semidirect products, which are absolutely continuous but not Lebesgue. We also show that there exist uncountably many pairwise non--conjugate mixing masas in the free group factors each with Puk\'{a}nszky invariant $\{1,\infty\}$.

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Jan Cameron, Junsheng Fang, Kunal Mukherjee. 2016-12-30. Mixing and weakly mixing abelian subalgebras of type II$_1$ factors. https://arxiv.org/abs/1612.09569

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