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Comportement asympotique des hauteurs des points de Heegner

Guillaume Ricotta, Nicolas Templier (2009)

Journal de Théorie des Nombres de Bordeaux

Le terme principal de la moyenne, sur les discriminants quadratiques satisfaisant la condition de Heegner, de la hauteur de Néron-Tate des points de Heegner d’une courbe elliptique rationnelle E a été déterminé dans [13]. Les auteurs ont également conjecturé l’expression du terme suivant. Dans cet article, il est démontré que cette expression est correcte et une asymptotique précise, qui sauve une puissance dans le terme d’erreur, est obtenue. Les annulations des coefficients de Fourier de formes...

Computations with Witt vectors of length 3

Luís R. A. Finotti (2011)

Journal de Théorie des Nombres de Bordeaux

In this paper we describe how to perform computations with Witt vectors of length 3 in an efficient way and give a formula that allows us to compute the third coordinate of the Greenberg transform of a polynomial directly. We apply these results to obtain information on the third coordinate of the j -invariant of the canonical lifting as a function on the j -invariant of the ordinary elliptic curve in characteristic p .

Computing modular degrees using L -functions

Christophe Delaunay (2003)

Journal de théorie des nombres de Bordeaux

We give an algorithm to compute the modular degree of an elliptic curve defined over ℚ . Our method is based on the computation of the special value at s = 2 of the symmetric square of the L -function attached to the elliptic curve. This method is quite efficient and easy to implement.

Computing the cardinality of CM elliptic curves using torsion points

François Morain (2007)

Journal de Théorie des Nombres de Bordeaux

Let ℰ / ℚ ¯ be an elliptic curve having complex multiplication by a given quadratic order of an imaginary quadratic field 𝕂 . The field of definition of ℰ is the ring class field Ω of the order. If the prime p splits completely in Ω , then we can reduce ℰ modulo one the factors of p and get a curve E defined over 𝔽 p . The trace of the Frobenius of E is known up to sign and we need a fast way to find this sign, in the context of the Elliptic Curve Primality Proving algorithm (ECPP). For this purpose, we propose...

Congruent numbers over real number fields

Tomasz Jędrzejak (2012)

Colloquium Mathematicae

It is classical that a natural number n is congruent iff the rank of ℚ -points on Eₙ: y² = x³-n²x is positive. In this paper, following Tada (2001), we consider generalised congruent numbers. We extend the above classical criterion to several infinite families of real number fields.

Conservative polynomials and yet another action of Gal ( ℚ ¯ / ℚ ) on plane trees

Fedor Pakovich (2008)

Journal de Théorie des Nombres de Bordeaux

In this paper we study an action D of the absolute Galois group Γ = Gal ( ℚ ¯ / ℚ ) on bicolored plane trees. In distinction with the similar action provided by the Grothendieck theory of “Dessins d’enfants” the action D is induced by the action of Γ on equivalence classes of conservative polynomials which are the simplest examples of postcritically finite rational functions. We establish some basic properties of the action D and compare it with the Grothendieck action.

Constructing elliptic curves over finite fields using double eta-quotients

Andreas Enge, Reinhard Schertz (2004)

Journal de Théorie des Nombres de Bordeaux

We examine a class of modular functions for Γ 0 ( N ) whose values generate ring class fields of imaginary quadratic orders. This fact leads to a new algorithm for constructing elliptic curves with complex multiplication. The difficulties arising when the genus of X 0 ( N ) is not zero are overcome by computing certain modular polynomials.Being a product of four η -functions, the proposed modular functions can be viewed as a natural generalisation of the functions examined by Weber and usually employed to construct...

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