Speaker

Gerard van der Geer is professor emeritus at the University of Amsterdam. He works in algebraic geometry and arithmetic geometry with emphasis on moduli spaces and modular forms. He worked on Hilbert modular surfaces,curves over finite fields, cycle classes on moduli of abelian varieties and on modular forms. He got a honorary doctorate of the University of Stockholm.

Personal Homepage：

http://van-der-geer.nl/~gerard/

Abstract

The cohomology of local systems on the moduli of principally polarized abelian varieties naturally harbours modular forms and their motives. The talk explains joint work with Faber and Bergström on the cohomology of local systems on the moduli of abelian varieties of dimension 2 and 3 and shows how it provides a lot of knowledge about Siegel modular forms.