On commencera par rappeler la théorie de Doeblin pour les systèmes conservatifs (semi-groupes de Markov) ainsi que le théorème de Harris qui la généralise via l’utilisation d’une fonction de Lyapunov. On présentera ensuite une méthode de renormalisation qui permet l’extension

This talk summarizes joint works by the speaker and Anne-Sophie Bonnet-Ben Dhia, Lucas Chesnel, Camille Carvalho and Juan-Pablo Borthagaray on how to solve problems with discontinuous, sign-changing coefficients. In electromagnetic theory, the effective response of specifically designed materials is modeled

We prove that the set of Lipschitz functions with the property of having a maximal Clarke subdifferential at every point contains a linear subspace of uncountable dimension. Our approach is constructive. In particular, in strong contrast to a previous result