On caractérise les puissances -ièmes dans un corps quadratique réel et dans à l’aide des polynômes de Dickson. Ces mêmes polynômes sont utilisés pour obtenir des renseignements sur l’indice du groupe des unités d’un ordre non-maximal dans le groupe de toutes les unités d’un corps quadratique réel. Le texte est détaillé et élémentaire.
In this paper we deal with the problem of finding the prime-ideal decomposition of a prime integer in a number field defined by an irreducible trinomial of the type , in terms of and . We also compute effectively the discriminant of .
Let be a Krull monoid with finite class group where every class contains some prime divisor. It is known that every set of lengths is an almost arithmetical multiprogression. We investigate which integers occur as differences of these progressions. In particular, we obtain upper bounds for the size of these differences. Then, we apply these results to show that, apart from one known exception, two elementary -groups have the same system of sets of lengths if and only if they are isomorphic.
There are many different definitions of the group of circular units of a real abelian field. The aim of this paper is to study their relations in the special case of a compositum k of real quadratic fields such that -1 is not a square in the genus field K of k in the narrow sense. The reason why fields of this type are considered is as follows. In such a field it is possible to define a group C of units (slightly bigger than Sinnott's group of circular units) such that the Galois...