On Popa's Cocycle Superrigidity Theorem

These notes contain an Ergodic-theoretic account of the Cocycle Superrigidity Theorem recently discovered by Sorin Popa. We state and prove a relative version of the result, discuss some applications to measurable equivalence relations, and point out that Gaussian actions (of ``rigid'' groups) satisfy the assumptions of Popa's theorem.

Authors: A. Furman,Bibliographical: Intern. Math. Res. Notices IMRN, {\bf 2007} (2007), 1--46, Art. ID rnm073.

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[Papers] [Alex Furman]