Companion forms and Kodaira-Spencer theory.
We show that if is an extremal even unimodular lattice of rank with , then is generated by its vectors of norms and . Our result is an extension of Ozeki’s result for the case .
Let be an elliptic curve defined over with conductor and denote by the modular parametrization:In this paper, we are concerned with the critical and ramification points of . In particular, we explain how we can obtain a more or less experimental study of these points.