Tentative de description immobilière de quelques représentations intégrales de groupes finis (avec l'aide de Guy Rousseau)
The aim of this paper is a new construction of bases of the group of circular units and of the Stickelberger ideal for a family of abelian fields containing all cyclotomic fields, namely for any compositum of imaginary abelian fields, each ramified only at one prime. In contrast to the previous papers on this topic our approach consists in an explicit construction of Ennola relations. This gives an explicit description of the torsion parts of odd and even universal ordinary distributions, but it...
We know that there exist only finitely many imaginary abelian number fields with class numbers equal to their genus class numbers. Such non-quadratic cyclic number fields are completely determined in [Lou2,4] and [CK]. In this paper we determine all non-cyclic abelian number fields with class numbers equal to their genus class numbers, thus the one class in each genus problem is solved, except for the imaginary quadratic number fields.
The so-called Lifted Root Number Conjecture is a strengthening of Chinburg’s - conjecture for Galois extensions of number fields. It is certainly more difficult than the -localization. Following the lead of Ritter and Weiss, we prove the Lifted Root Number Conjecture for the case that and the degree of is an odd prime, with another small restriction on ramification. The very explicit calculations with cyclotomic units use trees and some classical combinatorics for bookkeeping. An important...