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Loi de réciprocité quadratique dans les corps quadratiques imaginaires

Abdelmejid Bayad (1995)

Annales de l'institut Fourier

À partir d’une courbe elliptique définie sur le corps des classes de Hilbert d’un corps quadratique imaginaire K et à multiplicité complexe par l’anneau des entiers de K , on construit des fonctions elliptiques. Nous établissons des formules produits relatives à ces fonctions. De ce fait, nous obtenons une formulation analytique du lemme de Gauss généralisé ainsi qu’une expression explicite pour le symbole quadratique de Legendre défini sur l’anneau des entiers du corps quadratique imaginaire. Comme...

Loop groups, elliptic singularities and principal bundles over elliptic curves

Stefan Helmke, Peter Slodowy (2003)

Banach Center Publications

There is a well known relation between simple algebraic groups and simple singularities, cf. [5], [28]. The simple singularities appear as the generic singularity in codimension two of the unipotent variety of simple algebraic groups. Furthermore, the semi-universal deformation and the simultaneous resolution of the singularity can be constructed in terms of the algebraic group. The aim of these notes is to extend this kind of relation to loop groups and simple elliptic singularities. It is the...

Lower bounds on the class number of algebraic function fields defined over any finite field

Stéphane Ballet, Robert Rolland (2012)

Journal de Théorie des Nombres de Bordeaux

We give lower bounds on the number of effective divisors of degree g - 1 with respect to the number of places of certain degrees of an algebraic function field of genus g defined over a finite field. We deduce lower bounds for the class number which improve the Lachaud - Martin-Deschamps bounds and asymptotically reaches the Tsfasman-Vladut bounds. We give examples of towers of algebraic function fields having a large class number.

Matching local Witt invariants

Przemysław Koprowski (2005)

Acta Mathematica Universitatis Ostraviensis

The starting point of this note is the observation that the local condition used in the notion of a Hilbert-symbol equivalence and a quaternion-symbol equivalence — once it is expressed in terms of the Witt invariant — admits a natural generalisation. In this paper we show that for global function fields as well as the formally real function fields over a real closed field all the resulting equivalences coincide.

Minimal resolution and stable reduction of X 0 ( N )

Bas Edixhoven (1990)

Annales de l'institut Fourier

Let N 1 be an integer. Let X 0 ( N ) be the modular curve over Z , as constructed by Katz and Mazur. The minimal resolution of X 0 ( N ) over Z [ 1 / 6 ] is computed. Let p 5 be a prime, such that N = p 2 M , with M prime to p . Let n = ( p 2 - 1 ) / 2 . It is shown that X 0 ( N ) has stable reduction at p over Q [ p n ] , and the fibre at p of the stable model is computed.

Minimalité des courbes sous-canoniques

Mireille Martin-Deschamps (2002)

Annales de l’institut Fourier

Soient un fibré de rang 2 sur l’espace projectif de dimension 3 sur un corps algébriquement clos et n un entier tel que H 0 ( n - 1 ) = 0 et H 0 ( n ) 0 . Toute courbe C schéma des zéros d’une section non nulle de ( n ) est une courbe minimale dans sa classe de biliaison.

Currently displaying 941 – 960 of 2340