文摘
We prove that for any free ergodic nonsingular nonamenable action of all ¦£ in a large class of groups including all hyperbolic groups, the associated group measure space von Neumann algebra has as its unique Cartan subalgebra, up to unitary conjugacy. This generalizes the probability measure preserving case that was established in Popa and Vaes (in press) . We also prove primeness and indecomposability results for such crossed products, for the corresponding orbit equivalence relations and for arbitrary amalgamated free products over a subalgebra B of type I.