Lai-Sang Young (NYU Courant) (Videoconference)
TITLE :
Observable events and typical trajectories in finite and infiniteÌýdimensional dynamical systems
ABSTRACT :
The terms "observable events" and "typical trajectories" in the titleÌýshould really be between quotation marks, because what is typical and/orÌýobservable is a matter of interpretation. For dynamical systems onÌýfinite dimensional spaces, one often equates observable events withÌýpositive Lebesgue measure sets, and invariant distributions that reflectÌýthe large-time behaviors of positive Lebesgue measure sets of initialÌýconditions (such as Liouville measure for Hamiltonian systems) areÌýconsidered to be especially important. I will begin by introducing
these concepts for general dynamical systems -- including those withÌýattractors -- describing a simple dynamical picture that one might hopeÌýto be true. This picture does not always hold, unfortunately, but aÌýsmall amount of random noise will bring it about. In the second part ofÌýmy talk I will consider infinite dimensional systems such as semi-flowsÌýarising from dissipative evolutionary PDEs. I will discuss the extentÌýto which the ideas above can be generalized to infinite dimensions, andÌýpropose a notion of ``typical solutions".
PLACE :
Zoom meeting id:
ID de réunion : 170 851 981
Mot de passe : 942210
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