Riemann theta functions and Siegel modular forms Nom de l’orateur: Alessio Fiorentino Siegel modular forms are automorphic forms on the Siegel upper half-space with respect to congruence subgroups of the integer symplectic group and can be therefore used to embed moduli spaces of principally polarized abelian varieties in the complex projective spaces. This course aims at providing a basic introduction to Riemann theta functions with a particular focus on the major role they play in the theory of Siegel modular forms. This will also include a brief review of the classical structure theorems involving Riemann theta constants (Theta-Nullwerte) and of the main properties of the maps defined by these functions. 1