## Microlocal regularity of solutions to cohomological equations

### Vendredi 15 mai 15:00-16:00 - Thibault Lefeuvre - Université Paris-Saclay (Orsay)

Résumé : On a closed manifold endowed with a uniformly hyperbolic flow — or Anosov, in the literature —, a certain number of dynamical/geometrical problems (structural stability, marked length spectrum rigidity, study of transparent connections, ...) involve a class of equations called cohomological equations. Usually, one can construct by hand" a Hölder continuous solution to these equations but proving smoothness is harder. I will explain how one can relate the study of these equations to microlocal analysis. The key estimate to prove is a radial source estimate in Hölder-Zygmund spaces (and more generally, in Besov spaces), which is a kind of propagation of singularities in phase space. This was first used in the context of hyperbolic flows by Dyatlov-Zworski in Sobolev spaces. However, their proof is based on a positive commutator argument and the sharp Gärding inequality and does not seem to generalize to Hölder-Zygmund spaces. This is an ongoing project with Yannick Guedes Bonthonneau.

Lieu : https://bbb2.imo.universite-paris-saclay.fr/b/nic-m3v-7dt

Microlocal regularity of solutions to cohomological equations  Version PDF
juillet 2020 :
 Département de Mathématiques Bâtiment 307 Faculté des Sciences d'Orsay Université Paris-Saclay F-91405 Orsay Cedex Tél. : +33 (0) 1-69-15-79-56 Département Fermeture du département Laboratoire Formation