Hyperbolicity, automorphic forms and Siegel modular varieties

Hyperbolicity, automorphic forms and Siegel modular varieties

We study the hyperbolicity of compactifications of quotients of bounded symmetric domains by arithmetic groups. We prove that, up to an étale cover, they are Kobayashi hyperbolic modulo the boundary. Applying our techniques to Siegel modular varieties, we improve some former results of Nadel on the non-existence of certain level structures on abelian varieties over complex function fields.

Siegel Modular Forms

These are the lecture notes of the lectures on Siegel modular forms at the Nordfjordeid Summer School on Modular Forms and their Applications. We give a survey of Siegel modular forms and explain the joint work with Carel Faber on vector-valued Siegel modular forms of genus 2 and present evidence for a conjecture of Harder on congruences between Siegel modular forms of genus 1 and 2.

Codes and Siegel modular forms

It is proved that the ring of Siegel modular forms in any genus is determined by doubly-even self-dual codes and the theta relations. The (higher) weight polynomials of such codes are proved to be the generators of the ring of invariants of a polynomial ring in 2 g variables under a certain speciied nite group. Moreover codes are uniquely determined by their weight polynomials.

Siegel Modular Forms and Representations

This paper explicitly describes the procedure of associating an automorphic representation of PGSp(2n, A) with a Siegel modular form of degree n for the full modular group Γn = Sp(2n, Z), generalizing the well-known procedure for n = 1. This will show that the so-called “standard” and “spin” L-functions associated with such forms are obtained as Langlands L-functions. The theory of Euler produc...

Automorphic Forms on Shimura Varieties