Joint IAS/Princeton University Number Theory Seminar

Let S be a Shimura variety and L a set of special points on S. Andre and Oort conjecture that any irreducible component of the Zariski-closure of L is a subvariety of Hodge type of S. I will indicate a proof of this conjecture under GRH (this is joint work with A. Yafaev, relying on some work by Ullmo-Yafaev).