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Masas and Bimodule Decompositions of II_1 Factors

The measure-multiplicity-invariant for masas in II_1 factors was introduced by
Dykema, Smith and Sinclair to distinguish masas that have the same Pukanszky
invariant. In this dissertation, the measure class (left-right-measure) in the measuremultiplicity-
invariant is studied, which equivalent to studying the structure of the
standard Hilbert space as an associated bimodule. The focal point of this analysis
is: To what extent the associated bimodule remembers properties of the masa. The
structure of normaliser of any masa is characterized depending on this measure class,
by using Baire category methods (Selection principle of Jankov and von Neumann).
Measure theoretic proofs of Chifan's normaliser formula and the equivalence of weak
asymptotic homomorphism property (WAHP) and singularity is presented. Stronger
notions of singularity is also investigated. Analytical conditions based on Fourier
coefficients of certain measures are discussed, that partially characterize strongly
mixing masas and masas with nontrivial centralizing sequences. The analysis also
provide conditions in terms of operators and L2 vectors that characterize masas whose
left-right-measure belongs to the class of product measure. An example of a simple
masa in the hyperfinite II1 factor whose left-right-measure is the class of product
measure is exhibited. An example of a masa in the hyperfinite II1 factor whose leftright-
measure is singular to the product measure is also presented. Unitary conjugacy of masas is studied by providing examples of non unitary conjugate masas. Finally,
it is shown that for k greater than/equal to 2 and for each subset S \subseteq N, there exist uncountably many
non conjugate singular masas in L(Fk) whose Pukanszky invariant is S u {1}.

Identiferoai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2009-08-2937
Date2009 August 1900
CreatorsMukherjee, Kunal K.
ContributorsDykema, Kenneth J.
Source SetsTexas A and M University
Languageen_US
Detected LanguageEnglish
TypeBook, Thesis, Electronic Dissertation, text
Formatapplication/pdf

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