School Seminars and Colloquia

A property (T) free proof of Gaboriau-Popa

Set Theory Seminar

by Professor Greg Hjorth

Institution: The University of Melbourne, Mathematics and Statistics Department
Date: Thu 9th July 2009
Time: 4:15 PM
Location: Room 107, Richard Berry building, The University of Melbourne

Abstract: Gaboriau and Popa showed that a non-abelian free group has continuum many actions of a certain kind up to Orbit Equivalence. Their argument, and the related arguments in the following years, used the notion of property (T). I will sketch a far more elementary proof, which uses almost nothing beyond dynamics and topology.

For More Information: contact: Greg Hjorth. email