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SUMMARY:Property (T) and approximate conjugacy of actions - Andreas Aaseru
 d (Cardiff University)
DTSTART:20170420T090000Z
DTEND:20170420T100000Z
UID:TALK72100@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:I will define a notion of approximate conjugacy for probabilit
 y measure preserving actions and compare it to the a priori stronger class
 ical notion of conjugacy for such actions. In particular\, I will spend mo
 st of the talk explaining the proof of a theorem stating that two ergodic 
 actions of a fixed group with Kazhdan&#39\;s property (T) are approximatel
 y conjugate if and only if they are actually conjugate. Towards this end\,
  I will discuss some constructions from the theory of von Neumann algebras
 \, including the basic construction of Vaughan Jones and a version of the 
 Feldman-Moore construction. I will also provide some evidence that this th
 eorem may yield a characterization of groups with Kazhdan&#39\;s property 
 (T).  &nbsp\;  (Joint work with Sorin Popa)  <br><br><br><br>
LOCATION:Seminar Room 2\, Newton Institute
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