DUALITY FOR RELATIVE LOGARITHMIC DE RHAM-WITT SHEAVES ON SEMISTABLE SCHEMES OVER Fq [[t]]

We study duality theorems for the relative logarithmic de Rham-Witt sheaves on semi-stable schemes X over a local ring F-q[[t]], where F-q is a finite field. As an application, we obtain a new filtration on the maximal abelian quotient pi(ab)(1)(U) of the etale fundamental groups pi(1)(U) of an open subscheme U subset of X, which gives a measure of ramification along a divisor D with normal crossing and Supp(D) subset of X - U. This filtration coincides with the Brylinski-Kato-Matsuda filtration in the relative dimension zero case.