Displaying similar documents to “Hasse invariant and group cohomology.”

Congruences between Siegel modular forms on the level of group cohomology

Karsten Buecker (1996)

Annales de l'institut Fourier

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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 components of the cohomology are independent of the weight parameter. The meaning of 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...

Slopes of modular forms and congruences

Douglas L. Ulmer (1996)

Annales de l'institut Fourier

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Our aim in this paper is to prove congruences between on the one hand certain eigenforms of level p N and weight greater than 2 and on the other hand twists of eigenforms of level p N and weight 2. One knows that such congruences exist; the novelty here is that we determine the character of the form of weight 2 and the twist in terms of the slope of the higher weight form, i.e., in terms of the valuation of its eigenvalue for U p . Curiously, we also find a relation between the leading terms...