Iakovos Androulidakis
National and Kapodistrian University of Athens, Greece

Hypoelliptic differential operators play a central role in various fields, from stochastic analysis to contact and sub-riemannian geometry. A computable criterion of hypoellipticity was proposed by Helffer and Nourrigat in 1979. In this lecture we will give an overview of hypoellipticity and present the proof of the Helffer-Nourrigat conjecture. This is joint work with Omar Mohsen and Robert Yuncken.