Texas A&M University, Department of
Mathematics, 216 Milner Hall, 25th of February 2004, 3:00-4:00
Groups and Dynamcs Seminar
Superrigidity and
geometric splitting
Nicolas Monod of University of
Chicago
We prove general superrigidity results for actions of irreducible
lattices on CAT(0) spaces. In particular, one obtains a new proof of
Margulis' superrigidity theorem for uniform irreducible lattices in
non-simple
Lie (or algebraic) groups. The proofs rely on simple geometric
arguments, including a splitting theorem which can be viewed as an
infinite-dimensional (and singular) generalization of the
Gromoll-Wolf/Lawson-Yau theorem.