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 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...
Familles de fibrés vectoriels sur une surface de Riemann
Familles de revêtements de la droite projective
Fibrés exceptionnels et suite spectrale de Beilinson généralisée sur IP2 (C).
Fibrés exceptionnels et variétés de modules de faisceaux semi-stables sur P2 ( C ).
Fibrés génériques sur le plan projectif.
Fibrés stables de rang 2 sur JP2(C).
Fibrés stables et fibrés exceptionnels sur
Fibrés vectoriels de rang deux sur provenant d’un revêtement double
Depuis Schwarzenberger et son célèbre article intitulé « Vector bundles on the projective plane », on sait que tout fibré de rang deux sur peut être défini comme l’image directe d’un faisceau inversible sur une surface recouvrant doublement le plan. Ce théorème suggère d’étudier les fibrés de rang deux en fonction de la courbe de ramification du revêtement dont ils proviennent.Ainsi, dans la première partie on démontre que, étant donné un revêtement ramifié le long d’une courbe irréductible...
Fibrés vectoriels spéciaux
F-Isocrystales and De Rham Cohomology. I.
Fragmented deformations of primitive multiple curves
A primitive multiple curve is a Cohen-Macaulay irreducible projective curve Y that can be locally embedded in a smooth surface, and such that Y red is smooth. We study the deformations of Y to curves with smooth irreducible components, when the number of components is maximal (it is then the multiplicity n of Y). We are particularly interested in deformations to n disjoint smooth irreducible components, which are called fragmented deformations. We describe them completely. We give also a characterization...