Mon, 12 Nov 2007
14:45
14:45
L3
Kazhdan and Haagerup properties from the viewpoint of median spaces, applications to the mapping class groups
Cornelia Drutu
(Oxford)
Abstract
Both Kazhdan and Haagerup properties turn out to be related to actions
of
groups on median spaces and on spaces with measured walls.
These relationships allows to study the connection between Kazhdan
property (T) and the fixed point property
for affine actions on $L^p$ spaces, on one hand.
On the other hand, they allow to discuss conjugacy classes of subgroups
with property (T) in Mapping Class Groups. The latter result
is due to the existence of a natural structure of measured walls
on the asymptotic cone of a Mapping Class Group.
The talk is on joint work with I. Chatterji and F. Haglund
(first part), and J. Behrstock and M. Sapir (second part).