Speaker :
 Professor Sinisa Slijepcevic (University of Zagreb) 
Title :

New construction of positive entropy invariant measures of twist maps 
Time :
 20180702 (Mon) 15:00  16:30 
Place : 
Seminar Room 722, Institute of Mathematics (NTU Campus) 
Abstract: 
We introduce a new measure of instability of area preserving twist diffeomorphisms, which generalizes the notions of angle of splitting of separatrices, and flux through a gap of a Cantori. As an example of application, we establish a sharp > 0 lower bound on the topological entropy in a neighbourhood of a hyperbolic, unique actionminimizing fixed point, assuming only no topological obstruction to diffusion, i.e. no homotopically nontrivial invariant circle consisting of orbits with the rotation number 0. 