Indecomposable integral quadratic forms over global function fields
We build on preceeding work of Serre, Esnault-Kahn-Viehweg and Kahn to establish a relation between invariants, in modulo 2 étale cohomology, attached to a tamely ramified covering of schemes with odd ramification indices. The first type of invariant is constructed using a natural quadratic form obtained from the covering. In the case of an extension of Dedekind domains, mains, this form is the square root of the inverse different equipped with the trace form. In the case of a covering of Riemann...
Let be a global field of characteristic not 2, and let be an irreducible polynomial. We show that a non-degenerate quadratic space has an isometry with minimal polynomial if and only if such an isometry exists over all the completions of . This gives a partial answer to a question of Milnor.