Speaker: Andreas Thom
Affiliation: Mathematisches Institut Göttingen
Title: L^2-Betti numbers for von Neumann algebras and derivations.
Time and Place: Monday, April 3, 3:00-3:55pm, Milner 317.
Abstract: Using algebraic properties of the ring of operators affiliated with a finite von Neumann algebra, we can give a description of the first L^2-Betti number of a tracial von Neumann algebra (in the sense of Connes and Shlyakhtenko) by derivations with values in a bi-module of affiliated operators. We prove several results concerning extensions of derivations from sub-algebras and restrictions to sub-algebras.