Scharen quadratischer Zahlkörper mit gleichgebauten Einheiten
Si est une extension abélienne de de degré impair, l’étude du 2-groupe des classes (au sens ordinaire) de (et même celle de la parité du nombre de classes de ) est non triviale, et les algorithmes connus ne dépassent guère le cas .L’expression analytique de s’interprète à l’aide d’indices convenables de groupes d’unités cyclotomiques (Hasse et Leopoldt) ; ce dernier point de vue permet une caractérisation de la parité de , en fonction de l’existence d’unités cyclotomiques totalement...
We introduce a new ideal of the p-adic Galois group-ring associated to a real abelian field and a related ideal for imaginary abelian fields, Both result from an equivariant, Kummer-type pairing applied to Stark units in a -tower of abelian fields, and is linked by explicit reciprocity to a third ideal studied more generally in [D. Solomon, Acta Arith. 143 (2010)]. This leads to a new and unifying framework for the Iwasawa theory of such fields including a real analogue of Stickelberger’s Theorem,...
Let ε be a quartic algebraic unit. We give necessary and sufficient conditions for (i) the quartic number field K = ℚ(ε) to contain an imaginary quadratic subfield, and (ii) for the ring of algebraic integers of K to be equal to ℤ[ε]. We also prove that the class number of such K's goes to infinity effectively with the discriminant of K.
Stark’s conjectures connect special units in number fields with special values of -functions attached to these fields. We consider the fundamental equality of Stark’s refined conjecture for the case of an abelian Galois group, and prove it when this group has exponent . For biquadratic extensions and most others, we prove more, establishing the conjecture in full.