文摘
For a local field F with finite residue field of characteristic p, we describe completely the structure of the filtered F p[G]-module K ?×?/K ?× p in characteristic 0 and ${K/\wp(K)}$ in characteristic p, where ${K=F(\root{p-1}\of{F^\times})}$ and G?= Gal(K|F). As an application, we give an elementary proof of Serre’s mass formula in degree p. We also determine the compositum C of all degree-p separable extensions with solvable galoisian closure over an arbitrary base field, and show that C is ${K(\root p\of{K^\times})}$ or ${K(\wp^{-1}(K))}$ , respectively, in the case of the local field F.