Wednesday, March 14, 2012 - 11:00
1 hour (actually 50 minutes)
Hyperbolic actions of Z^k and R^k arise naturally in algebraic and geometric context. Algebraic examples include actions by commuting automorphisms of tori or nilmanifolds and, more generally, affine and homogeneous actions on cosets of Lie groups. In contrast to hyperbolic actions of Z and R, i.e. Anosov diffeomorphisms and flows, higher rank actions exhibit remarkable rigidity properties, such as scarcity of invariant measures and smooth conjugacy to a small perturbation. I will give an overview of results in this area and discuss recent progress.