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Colloquium
Thursday, October 31, 2013


Von Neumann algebras and ergodic theory of group actions

Stefaan Vaes (Leuven)


Abstract: The subject of this talk is at the crossroads of functional analysis, ergodic theory and group theory. Using a construction by Murray and von Neumann (1943), countable groups and their ergodic actions on measure spaces give rise to algebras of operators on a Hilbert space, called von Neumann algebras. A famous problem asks whether the group von Neumann algebras L(Fn) associated with the free groups with n generators, Fn, are non-isomorphic for distinct n's.While this problem is still open, its ``group measure space'' version has been settled by Sorin Popa and myself. I will comment on this, as well as on related classification results for von Neumann algebras established within Popa's deformation/rigidity program.

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Location :  Room 611 of the Hans Freudenthal building, formerly known as the Wiskunde/Maths building, (campus De Uithof) Budapestlaan 6, Utrecht.
Date and time : Thursday, October 31, 2013 15:30-16:30. The lecture is preceded by coffee, tea, and cookies from 15.00 to 15.30 hour in the same room.