Équations différentielles -adiques et dégénérescence de groupes de Hodge
Equivariant degenerations of spherical modules for groups of type
V. Alexeev and M. Brion introduced, for a given a complex reductive group, a moduli scheme of affine spherical varieties with prescribed weight monoid. We provide new examples of this moduli scheme by proving that it is an affine space when the given group is of type and the prescribed weight monoid is that of a spherical module.
Errata-Corrige : “Canonical surfaces with and ”
Erratum to : Morphisms, line bundles and moduli spaces in real algebraic geometry
Everywhere non reduced moduli spaces.
Explicit resolution of local singularities of moduli-spaces.
Extension of maps defined on many fibres.
Let S be a fibred surface. We prove that the existence of morphisms from non countably many fibres to curves implies, up to base change, the existence of a rational map from S to another surface fibred over the same base reflecting the properties of the original morphisms. Under some conditions of unicity base change is not needed and one recovers exactly the initial maps.
Extension of mixed Hodge modules
Extremal rays on smooth threefolds
Factoring polynomials in finite fields: an application of Lang-Weil to a problem in graph theory.
Factorisation of generalised theta functions. I.
Factorization of rank two theta functions. II. Proof of the Verlinde formula.
Faisceaux cohérents sur les courbes multiples.
This paper is devoted to the study of coherent sheaves on non reduced curves that can be locally embedded in smooth surfaces. If Y is such a curve then there is a filtration C ⊂ C2 ⊂ ... ⊂ Cn = Y such that C is the reduced curve associated to Y, and for very P ∈ C there exists z ∈ OY,P such that (zi) is the ideal of Ci in OY,P. We define, using canonical filtrations, new invariants of coherent sheaves on Y: the generalized rank and degree, and use them to state a Riemann-Roch theorem for sheaves...
Families of Curves on Surfaces.
Families of Curves with Nodes on K-3 Surfaces.
Families of linear differential equations related to the second Painlevé equation
This paper is a sequel to [vdP-Sa] and [vdP]. The two classes of differential modules (0,-,3/2) and (-,-,3), related to PII, are interpreted as fine moduli spaces. It is shown that these moduli spaces coincide with the Okamoto-Painlevé spaces for the given parameters. The geometry of the moduli spaces leads to a proof of the Painlevé property for PII in standard form and in the Flaschka-Newell form. The Bäcklund transformations, the rational solutions and the Riccati solutions for PII are derived...
Families of varieties with prescribed singularities
Familles de fibrés vectoriels sur une surface de Riemann
Familles de Hurwitz et cohomologie non abélienne
Nous nous intéressons à la question de l’existence de familles de Hurwitz au-dessus d’un espace de modules de revêtements de la droite. On sait que de telles familles existent dans le cas où les revêtements n’ont pas d’automorphismes. Dans le cas général, il y a une obstruction cohomologique, de nature non-abélienne. Nous donnons une double description de cette obstruction : la première en termes de gerbe, l’outil le mieux adapté à des situations cohomologiques non-abéliennes et la deuxièmes en...
Familles de revêtements de la droite projective