Betti numbers invariants
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We prove that a type II1 factor M can have at most one Cartan subalgebra A satisfying a combination of rigidity and compact approximation properties. We use this result to show that within the class HT of factors M having such Cartan subalgebras A ⊂ M , the Betti numbers of the standard equivalence relation associated with A ⊂ M ([G2]), are in fact isomorphism invariants for HT the factors M , βn (M ), n ≥ 0. The class HT is closed under amplifications HT HT and tensor products,
92p noel_noel 17-01-2013 38 7 Download