Abstract

Let X be a fine and saturated log scheme, and let G be a commutative finite flat group scheme over the underlying scheme of X. If G-torsors for the fppf topology can be thought of as being unramified objects by nature, then G-torsors for the log flat topology allow us to consider tame ramification. Using the results of Kato, we define a concept of Galois structure for these torsors, then we generalize the author's previous constructions (class-invariant homomorphism for semi-stable abelian varieties) in this new setting, thus dropping some restrictions.