Torsion dans un produit de courbes elliptiques

Critères d'irréductibilité pour les représentations des courbes elliptiques

Let $E$ be an elliptic curve defined over a number field $K$. We say that a prime number $p$ is exceptional for $(E,K)$ if $E$ admits a $p$-isogeny defined over $K$. The so-called exceptional set of all such prime numbers is finite if and only if $E$ does not have complex multiplication over K. In this paper, we prove that the exceptional set is included in the set of prime divisors of an explicit list of integers (depending on $E$ and $K$), whose infinitely many of them are non-zero. It provides an efficient algorithm for computing it in the finite case. Other less general but rather useful c…

Equivalence rationnelle, equivalence numerique et produits de courbes elliptiques sur un corps fini

This is an update of the first version. We clarify that the main results apply to more general smooth projective varieties X than products of elliptic curves (briefly: X is of "abelian type", e.g. an abelian variety or a product of curves, and the Tate conjecture holds). We also deduce the Gersten conjecture for dvrs whose residue field is the function field of such an X. In an appendix, we construct some functoriality for etale motivic cohomology. Finally, some errors which were in Section 5 of the first version are corrected.

Familles de polynomes liees aux courbes modulaires X_1(l) unicursales et points rationnels non-triviaux de courbes elliptiques quotient

Soit l un entier et E_{c,l} la famille de Kubert des courbes elliptiques definies sur Q munies d'un point rationnel A d'ordre l. On note F_{c,l} la courbe elliptique quotient de E_{c,l} par le groupe engendre' par A, et f_l l'isogenie de E_{c,l} sur F_{c,l}. Pour l = 3, 4, 5 et 6, nous construisons explicitement, pour des parametrisations convenables de c, des elements non-triviaux de F_{c,l}(Q) / (f_l(E_{c,l}(Q))), autrement dit, des points explicites de F_{c,l}(Q) qui ne sont l'image par f_l d'aucun element de E_{c,l}(Q). Ces points sont en general d'ordre infini. Nous donnons des applicatio…

Les représentations ell-adiques associées aux courbes elliptiques sur \Q_p

This paper is devoted to the study of the $\ell$-adic representations of the absolute Galois group $G$ of ${\mathbb Q}_p$, $p\geq 5$, associated to an elliptic curve over ${\mathbb Q}_p$, as $\ell$ runs through the set of all prime numbers (including $\ell =p$, in which case we use the theory of potentially semi-stable $p$-adic representations). For each prime $\ell$, we give the complete list of isomorphism classes of ${\mathbb Q}_{\ell}[G]$-modules coming from an elliptic curve over ${\mathbb Q}_p$, that is, those which are isomorphic to the Tate module of an elliptic curve over ${\mathbb Q}…

Produit eulérien motivique et courbes rationnelles sur les variétés toriques

We study the asymptotical behaviour of the moduli space of morphisms of given anticanonical degree from a rational curve to a split toric variety, when the degree goes to infinity. We obtain in this case a geometric analogue of Manin's conjecture about rational points of bounded height on varieties defined over a global field. The study is led through a generating series whose coefficients lie in a Grothendieck ring of motives, the motivic height zeta function. In order to establish convergence properties of this function, we use a notion of eulerian motivic product. It relies on a constructio…

Approximation diophantienne sur une courbe elliptique

We present here quantitative versions in 1 dimension of Faltings'theorem according to which the set of the K-rational points (where K is a given number field) of an abelian variety A definied over K, which are close (with respect to a v-adic distance on K) to some K-subvariety X of A, but not belonging to X, is finite. We treat more exactly the case where A is an elliptic curve and X is reduced to a point of A and we give (in this case) explicit bounds for the cardinal of the exceptional finite set. We consider also, more generally, instead of only one place v of K, a finite set S of places of…

Theoreme de Dobrowolski-Laurent pour les extensions abeliennes sur une courbe elliptique a multiplication complexe

Let E/K be an elliptic curve with complex multiplication and let $K^{ab}$ be the Abelian closure of $K$. We prove in this article that there exists a constant $c(E/K)$ such that : for all point $P\in E(\bar{K})-E_{tors}$, we have \[\hat{h}(P)\geq\frac{c(E/K)}{D}(\frac{\log \log 5D}{\log 2D})^{13},\] where $D=[K^{ab}(P):K^{ab}]$. This result extends to the case of elliptic curve s with complex multiplication the previous resultof Amoroso-Zannier \cite{AZ} on the analogous problem on the multiplicative group $\mathbb{G}_m$, and generalizes to the case of extensions of degree D the result of Bake…

椭圆曲线与 Drinfeld 模的统一定义

Pour une définition commune des courbes elliptiques et modules de Drinfeld

本文为椭圆曲线与 Drinfeld 模提出统一代数定义，引入“模 élémentaires”并给出其分类，将两者类比提升为统一理论。

Sur la conjecture de Tate entière pour le produit d'une courbe et d'une surface $CH_{0}$-triviale sur un corps fini

We investigate a strong version of the integral Tate conjecture for 1-cycles on the product of a curve and a surface over a finite field, under the assumption that the surface is geometrically $CH_0$-trivial. By this we mean that over any algebraically closed field extension, the degree map on the zero-dimensional Chow group of the surface is an isomorphism. This applies to Enriques surfaces. When the Néron-Severi group has no torsion, we recover earlier results of A. Pirutka. The results rely on a detailed study of the third unramified cohomology group of specific products of varieties.

Sur la cohomologie non ramifiée en degré trois d'un produit

Let F be a finite field and let C be a smooth projective curve over F. For some smooth projective surfaces X over F we establish that the third unramified cohomology of the product of X and C vanishes. This applies in particular to geometrically rational surfaces. Soit F un corps fini et soit C une courbe projective et lisse sur F. Pour certaines surfaces projectives et lisses X sur F on établit la nullité du troisième groupe de cohomologie non ramifiée du produit de X et C. Cela s'applique en particulier aux surfaces géométriquement rationnelles.

Zéro-cycles sur les fibrations au-dessus d'une courbe de genre quelconque

Let X be a smooth and proper variety over a number field k. Conjectures on the image of the Chow group of zero-cycles of X in the product of the corresponding groups over all completions of k were put forward by Colliot-Thélène, Kato and Saito. We prove these conjectures for the total space of fibrations, over curves with finite Tate-Shafarevich group, into rationally connected varieties which satisfy weak approximation, under an abelianness assumption on the singular fibers. ---- Soit X une variété propre et lisse sur un corps de nombres k. Des conjectures sur l'image du groupe de Chow des zé…

Compter (rapidement) le nombre de solutions d'équations dans les corps finis

The number of solutions in finite fields of a system of polynomial equations obeys a very strong regularity, reflected for example by the rationality of the zeta function of an algebraic variety defined over a finite field, or the modularity of Hasse-Weil's $L$-function of an elliptic curve over $\Q$. Since two decades, efficient methods have been invented to compute effectively this number of solutions, notably in view of cryptographic applications. This exposé presents some of these methods, generally relying on the use of Lefshetz's trace formula in an adequate cohomology theory and discuss…