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Congruences between modular forms and lowering the level mod n

Luis Dieulefait, Xavier Taixés i Ventosa (2009)

Journal de Théorie des Nombres de Bordeaux

In this article we study the behavior of inertia groups for modular Galois mod n representations and in some cases we give a generalization of Ribet’s lowering the level result (cf. [9]).

Congruences between Siegel modular forms on the level of group cohomology

Karsten Buecker (1996)

Annales de l'institut Fourier

Vector-valued Siegel modular forms may be found in certain cohomology groups with coefficients lying in an irreducible representation of the symplectic group. Using functoriality in the coefficients, we show that the ordinary components of the cohomology are independent of the weight parameter. The meaning of ordinary depends on a choice of parabolic subgroup of G S p ( 4 ) , giving a particular direction in the change of weight. Our results complement those of Taylor and Tilouine-Urban for the two other possible...

Congruences for Siegel modular forms

Dohoon Choi, YoungJu Choie, Olav K. Richter (2011)

Annales de l’institut Fourier

We employ recent results on Jacobi forms to investigate congruences and filtrations of Siegel modular forms of degree 2 . In particular, we determine when an analog of Atkin’s U ( p ) -operator applied to a Siegel modular form of degree 2 is nonzero modulo a prime p . Furthermore, we discuss explicit examples to illustrate our results.

Congruences modulo between ϵ factors for cuspidal representations of G L ( 2 )

Marie-France Vignéras (2000)

Journal de théorie des nombres de Bordeaux

Let p be two different prime numbers, let F be a local non archimedean field of residual characteristic p , and let 𝐐 ¯ , 𝐙 ¯ , 𝐅 ¯ be an algebraic closure of the field of -adic numbers 𝐐 , the ring of integers of 𝐐 ¯ , the residual field of 𝐙 ¯ . We proved the existence and the unicity of a Langlands local correspondence over 𝐅 ¯ for all n 2 , compatible with the reduction modulo in [V5], without using L and ϵ factors of pairs. We conjecture that the Langlands local correspondence over 𝐐 ¯ respects congruences modulo between...

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...

Constructing modular forms from harmonic Maass Jacobi forms

Ran Xiong, Haigang Zhou (2021)

Czechoslovak Mathematical Journal

We construct a family of modular forms from harmonic Maass Jacobi forms by considering their Taylor expansion and using the method of holomorphic projection. As an application we present a certain type Hurwitz class relations which can be viewed as a generalization of Mertens' result in M. H. Mertens (2016).

Construction de formes automorphes réflectives sur un espace de dimension 4

Caroline Desreumaux (2006)

Journal de Théorie des Nombres de Bordeaux

Dans la lignée des travaux de V. Gritsenko et V. Nikulin, par des méthodes reliées aux formes de Jacobi définies relativement au réseau de racines A 2 , on construit six formes automorphes réflectives qui seront associées à des algèbres de Kac–Moody hyperboliques de type de Borcherds, pour la signature ( 1 , 3 ) , et, pour quatre d’entre elles, on précisera une identité du type “formule du dénominateur”, déterminant entièrement l’algèbre en question.

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