Traces and Differential Operators over Beilinson Completion Algebras

Abstract

A Beilinson completion algebra (BCA) A is a complete semilocal algebra over a perfect field k, whose residue fields are high dimensional local fields. In addition A is a semi-topological algebra. The completion of the structure sheaf of an algebraic k-variety along a saturated chain of points is the prototypical example of a BCA. We single out two kinds of homomorphisms between BCAs: morphisms and intensifications. The first kind includes residually finite local homomorphisms, whereas the second kind is a sort of localization. We prove that every BCA A has a dual module K(A), and these dual modules are contravariant w.r.t. morphisms and covariant w.r.t. intensifications. For any semi-topological A-module M we define its dual Dual_{A} M := Hom_{A}^{cont}(M, K(A)). This duality operation has the remarkable property of respecting differential operators: given a continuous DO D : M --> N, there is a dual DO Dual_{A}(D) : Dual_{A} N --> Dual_{A} M. The results above are used (in a subsequent paper) to construct the Grothendieck residue complex K_{X}^{.} on any finite type k-scheme X, and to derive many of its properties.