Galois module structure of psth power classes of a field
When a field K contains a primitive pth root of unity, Kummer theory tells us that the Fp-space K×p/K× is a parameterizing space for elementary p-abelian extensions of K. In previous work, the authors computed the Galois module structure of this set when the Galois group came from an extension K/F whose Galois group is isomorphic to Z/pnZ. In this talk we consider the more refined group K×ps/K× as a Galois module, and we determine its structure. Although the modular representation theory in this case is unwieldy, it turns out that there is only one summand in the decomposition of K×ps/K× which is not free (either under the full ring or one of its natural quotients). Furthermore, this "exceptional" summand's structure is connected to the cyclotomic character and a certain family of embedding problems along the tower K/F. This work is joint with J\'{a}n Min\'{a}\v{c} and John Swallow.