Le vendredi 12 octobre 2018 à 11:15 - salle 430Laurent Miclo
Higer order Cheeger inequalities give lower bounds on the $n$-th eigenvalue of the Laplacian on a compact Riemannian manifold $M$ in terms of isoperimetric ratios associated to some optimal partitions of $M$ into $n$ subsets. They generalizes the minimal cut of $M$ into two parts to get a lower bound of the spectral gap. The talk will show how to extend such bounds to Steklov operators on the boundary of $M$ (also known as Dirichlet to Neumann operators). Similar results will also presented in the corresponding probabilist contexts of finite and measurable state spaces. Work in collaboration with Asma Hassannezhad (Bristol).