Base Number Theorem for Abelian Varieties. An Infinitesimal Approach.
In this paper the equality is established of three different pairings between the first de Rham cohomology group of an abelian scheme over a base flat over and that of its dual. These pairings have appeared and been used either explicitly or implicitly in the literature.In the last section we deduce a generalization to arbitrary characteristic of Serre’s formula for the Poincaré pairing on the first de Rham cohomology group of a curve over a field of characteristic zero.
In this paper we study the étale cohomology groups associated to abelian varieties. We obtain necessary and sufficient conditions for an abelian variety to have semistable reduction (or purely additive reduction which becomes semistable over a quadratic extension) in terms of the action of the absolute inertia group on the étale cohomology groups with finite coefficients.