Deligne's duality for de Rham realizations of 1‐motives

Abstract

Abstract Let M be a 1‐motive over a base scheme S and M ′ its Cartier dual. We show the existence of a canonical duality between the de Rham realizations of M and M ′; this generalizes a result in [5]. Furthermore, we study universal extensions of 1‐motives and their relation with ♮‐extensions (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)