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Creators/Authors contains: "Popa, Sorin"

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  1. We prove that, under the continuum hypothesis c = א1, any ul- traproduct II1 factor M = ∏ Mn of separable finite factors Mn contains more ω than c many mutually disjoint singular MASAs, in other words the singular abelian rank of M, r(M), is larger than c. Moreover, if the strong continuum hypothesis 2c = א2 is assumed, then r(M) = 2c. More generally, these results hold true for any II1 factor M with unitary group of cardinality c that satisfies the bicommutant condition (A0′ ∩ M)′ ∩ M = M, for all A0 ⊂ M separable abelian. 
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  2. Abstract We prove that ifAis a non-separable abelian tracial von Neuman algebra then its free powersA∗n,2≤n≤∞, are mutually non-isomorphic and with trivial fundamental group,$$\mathcal{F}(A^{*n})=1$$, whenever 2≤n<∞. This settles the non-separable version of the free group factor problem. 
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