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Calendar - NCG group

Events on Wednesday October 10, 2012

SYM lecture
Survey on the classication of von Neumann factors of type II_1
Speaker(s): Narutaka Ozawa
(Kyoto)
Wednesday October 10, 2012 at 12:05-13:00. Place: Aud 8. Language: English.

This is a public lecture in the monthly SYM lecture series.

It is colloquium style, and supposed to be accessible to all SYM members.

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In the early 40s, Murray and von Neumann found that discrete groups and their measure-preserving actions on probability spaces give rise to von Neumann factors of type II_1, and posed the classification problem. Thirty years later, Connes gave the celebrated classification theorem for injective von Neumann algebras which implies the uniqueness of von Neumann factors arising from amenable groups (and their actions).

Even though the complete classification beyond amenable cases is impossibly di cult, one tries to distinguish them as much as one can. A decade ago, Popa discovered that the tension between amenability and rigidity can be used to unfold the structure of factors of type II_1. Since Popa's breakthrough, the classification theory of von Neumann factors of type II_1 has seen remarkable progress. It also found exciting interaction with ergodic and geometric group theory and descriptive set theory. I will survey these progresses, with an emphasis on rigidity phenomena in the classication theory.

Organized by JG

Centre for Symmetry and Deformation

Operator algebra seminar
Canceled due to too many staff members out of town
Speaker(s): Tyrone Crisp
(IMF KU)
Wednesday October 10, 2012 at 15:15-16:15. Place: Aud 9. Language: English.

Tyrone's talk will be presented when more staff members are able to attend.

Organized by Erik Christensen, Søren Eilers