Transitivity of nilpotent extensions of hyperbolic systems

CDSNS Colloquium
Monday, February 27, 2012 - 11:05am
1 hour (actually 50 minutes)
Skiles 006
Univ. of Houston
Consider a hyperbolic basic set of a smooth diffeomorphism. We are interested in the transitivity of Holder skew-extensions with fiber a non-compact connected Lie group. In the case of compact fibers, the transitive extensions contain an open and dense set. For the non-compact case, we conjectured that this is still true within the set of extensions that avoid the obvious obstructions to transitivity. Within this class of cocycles, we proved generic transitivity for extensions with fiber the special Euclidean group SE(2n+1) (the case SE(2n) was known earlier), general Euclidean-type groups, and some nilpotent groups. We will discuss the "correct" result for extensions by the Heisenberg group: if the induced extension into its abelinization is transitive, then so is the original extension. Based on earlier results, this implies the conjecture for Heisenberg groups. The results for nilpotent groups involve questions about Diophantine approximations. This is joint work with Ian Melbourne and Viorel Nitica.