A generalization of class formation by using hypercohomology.
A Brückner-Vostokov formula for the Hilbert symbol of a formal group was established by Abrashkin under the assumption that roots of unity belong to the base field. The main motivation of this work is to remove this hypothesis. It is obtained by combining methods of ()-modules and a cohomological interpretation of Abrashkin’s technique. To do this, we build ()-modules adapted to the false Tate curve extension and generalize some related tools like the Herr complex with explicit formulas for the...
Let be a finite extension of , let , respectively , be the division fields of level , respectively , arising from a Lubin-Tate formal group over , and let Gal(). It is known that the valuation ring cannot be free over its associated order in unless . We determine explicitly under the hypothesis that the absolute ramification index of is sufficiently large.
Let be a -adic field. We give an explicit characterization of the abelian extensions of of degree by relating the coefficients of the generating polynomials of extensions of degree to the exponents of generators of the norm group . This is applied in an algorithm for the construction of class fields of degree , which yields an algorithm for the computation of class fields in general.
Soit un entier . Pour un nombre premier on note l’extension maximale non ramifiée de . Supposons que divise exactement . Alors, en utilisant les travaux de Carayol et la théorie du corps de classes local, on détermine une extension de sur laquelle la jacobienne de la courbe modulaire de admet une réduction semi-stable, puis on donne une estimation de son degré.