Galois modules torsion in Number fields

Let E be a number fields with ring of integers R and N be a tame galois extension of E with group G. The ring of integers S of N is an RG-module so an ZG-module. In this book we study some other RG-modules which appear in the study of the module structure of S as RG-module. We will compute their Hom-representatives in Frohlich Hom-description using Stickelberger’s factorisation and show their triviliaty in the class group Cl(ZG).