Self-dual normal bases for infinite odd abelian Galois ring extensions
Let p be a rational prime, G a group of order p, and K a number field containing a primitive pth root of unity. We show that every tamely ramified Galois extension of K with Galois group isomorphic to G has a normal integral basis if and only if for every Galois extension L/K with Galois group isomorphic to G, the ring of integers in L is free as a module over the associated order . We also give examples, some of which show that this result can still hold without the assumption that K contains...
The Steinitz class of a number field extension is an ideal class in the ring of integers of , which, together with the degree of the extension determines the -module structure of . We denote by the set of classes which are Steinitz classes of a tamely ramified -extension of . We will say that those classes are realizable for the group ; it is conjectured that the set of realizable classes is always a group.In this paper we will develop some of the ideas contained in [7] to obtain some...
Soient le groupe de Galois d’une extension galoisienne finie, , d’un corps de nombres et un ensemble de places de , contenant les places de sauvagement ramifiées dans . Nous démontrons, dans de nombreux cas particuliers, une conjecture faite par J. Queyrut dans un article précédent : l’ordre de la classe de l’anneau des entiers de , dans le sous-groupe de torsion du groupe de Grothendieck des -module localement libres en dehors de , est égal à 1 ou 2, selon le signe des constantes...