Winter 2017/2018
Oberseminar Nonlinear Dynamics
Organizers
Program
Oct 17, 2017 
Jan Sieber (University of Exeter) 
Smooth center manifolds for delaydifferential equations 
Abstract: Delaydifferential equations (DDEs) with statedependent delays
are, as far as is known, at best continuously differentiable once as
dynamical systems. That is, the timet map does not depend on its argument
with a higher degree of smoothness than 1. However, as I will show, center
manifolds near equilibria are still as smooth as expected from the spectral
gap and from the smoothness of coefficients. In particular, I will review
what precisely "smoothness of coefficients" means.

Oct 24, 2017 
Carlos Rocha (Instituto Superior Técnico of Lisbon) 
Global Attractors for Nonautonomous Systems 
We survey the notions of global attractors for nonautonomous systems, and consider small nonautonomous perturbations of dynamical systems to discuss the resulting changes on the global attractors. We review the notion of MorseSmale dynamical system and extend this notion to the nonautonomous framework, based on a recent joint work with R. Czaja and W. Oliva.

Nov 7, 2017 
Cancelled 
Nov 14, 2017 
Cancelled 
Oct 24, 2017 
Nikita Begun (Saint Petersburg State University) 
Chaos for the saw map 
We consider dynamics of a scalar piecewise linear "saw map" with infinitely many linear segments. In particular, such a map occurs as the Poincare map of simple twodimensional discrete time piecewise linear systems involving a saturation function. Alternatively, these systems can be viewed as systems with a feedback loop containing the hysteretic stop operator. We analyze chaotic sets and attractors of the ''saw map'' depending on its parameters.

Time and Place
Talks usually take place on Tuesday at 3:15 p.m.
at the Free University Berlin
Arnimallee 7 (rear building), room 140.
Tea/coffee at 2:45 p.m.
Arnimallee 3 (rear building), room 136 (kitchen).
Guests are always welcome !
Archive
