Vorträge in der Woche 15.02.2010 bis 21.02.2010

Donnerstag, 18.02.2010: Littlewood and Large Forests

Nicolas Monod

Motivated by a classical result of Sz.-Nagy in functional analysis, J. Dixmier asked in 1950 which group representations can be made unitary. This question is still open, but I will report on some progress obtained with Epstein and Ozawa. We approach the question with ideas borrowed from XIXth century electricity theory as well as from contemporary percolation theory. As a result, we obtain notably non-unitarizable representations for Burnside groups and a new characterization of amenability. The talk will be expository.