Matthew Foreman: Better lucky than smart: realizing a quasi-generic class of measure preserving transformations as diffeomorphisms

HUJI Logic Seminar

 

The next meeting of the Logic Seminar will be in Wednesday, 28/12/16, 16:00 – 18:00, in Ross Building, 70.

Title: Better lucky than smart: realizing a quasi-generic class of measure preserving transformations as diffeomorphisms.
Speaker: Matthew Foreman
Abstract: In 1932, von Neumann proposed classifying measure preserving diffeomorphisms up to measure isomorphism. Joint work with B. Weiss shows this is impossible in the sense that the corresponding equivalence relation is not Borel; hence impossible to capture using countable methods.

An accidental consequence of the proof addresses a different classical problem: which measure preserving transformations are isomorphic to diffeomorphisms of a compact smooth manifold?
In this talk we discuss the proof that  a quasi-generic class of measure preserving transformations are isomorphic to measure preserving diffeomorphisms of the torus.

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