A hunt for spectral gaps (Rostislav GRIGORCHUK, Texas A&M University)

06.11.2025 16:15

In my talk I will describe an approach to studying spectra of groups and graphs which originated thirty years ago during my first visit to Geneva and was developed in collaboration with Laurent Bartholdi, Pierre de la Harpe, Tatiana Nagnibeda, Christophe Pittet and other colleagues. We will discuss such topics as graphs whose spectrum is a Cantor set, pure point spectrum vs continuous spectrum, the question of Alain Valette "Can one hear the shape of a group? ", Ramanujan graphs coming from automata groups.

Le colloque sera suivi d'un apéritif

Lieu

Bâtiment: Conseil Général 7-9

Salle 1-15, Colloque de mathématiques

entrée libre