Sur les variétés de base simples des transformations de Cremona
Sur les variétés telles que par points passe une courbe de de degré donné
Soit , , et des entiers. On introduit la classe des sous-variétés de dimension d’un espace projectif, telles que pour générique, il existe une courbe rationnelle normale de degré , contenue dans et passant par les points ; engendre un espace projectif dont la dimension, pour , et donnés, est la plus grande possible compte tenu de la première propriété. Sous l’hypothèse , on détermine toutes les variétés appartenant à la classe . On montre en particulier qu’il existe une...
Surfaces de type général dominées par une variété fixe
Surfaces d'Enriques et une construction de surfaces de type général avec pg = 0.
Surfaces in with no quadrisecant lines.
Surfaces of order 1 in Grassmannians.
Surfaces rationnelles non-spéciales dans IP4.
Syzygies and logarithmic vector fields along plane curves
We investigate the relations between the syzygies of the Jacobian ideal of the defining equation for a plane curve and the stability of the sheaf of logarithmic vector fields along , the freeness of the divisor and the Torelli properties of (in the sense of Dolgachev-Kapranov). We show in particular that curves with a small number of nodes and cusps are Torelli in this sense.
Syzygies of abelian surfaces embedded in ... (...).
Tautological relations and the -spin Witten conjecture
In [11], A. Givental introduced a group action on the space of Gromov–Witten potentials and proved its transitivity on the semi-simple potentials. In [24, 25], Y.-P. Lee showed, modulo certain results announced by C. Teleman, that this action respects the tautological relations in the cohomology ring of the moduli space of stable pointed curves. Here we give a simpler proof of this result. In particular, it implies that in any semi-simple Gromov–Witten theory where arbitrary correlators can be...
Teorema de irreducibilidad para correspondencias algebraicas.
Sea T una correspondencia algebraica irreducible entre dos variedades proyectivas, V y V', sobre un cuerpo k algebraicamente cerrado y de característica cero. Sea W una subvariedad irreducible de V y W' = T{W} la transformada total de W en T. En [1] se estudia el problema de la conexión de W' y en [3] se estudia el problema de la irreducibilidad de la transformada total de W en correspondencias locales. La finalidad de este artículo es la de aprovechar los resultados de los dos trabajos citados,...
The automorphism group of
The paper studies fiber type morphisms between moduli spaces of pointed rational curves. Via Kapranov’s description we are able to prove that the only such morphisms are forgetful maps. This allows us to show that the automorphism group of is the permutation group on elements as soon as .
The Clifford dimension of a projective curve
The complex separation of real surfaces and extensions of Rokhlin congruence.
The Cubo-Cubic Transformation of IP3 is Very Special.
The curve , is not set-theoretic complete intersection of two quartic surfaces
The degree of the secant variety and the join of monomial curves.
A monomial curve is a curve parametrized by monomials. The degree of the secant variety of a monomial curve is given in terms of the sequence of exponents of the monomials defining the curve. Likewise, the degree of the join of two monomial curves is given in terms of the two sequences of exponents.
The density of S-integral points in projective space with respect to a quadric
The (dimension + 2)-secant Lemma.
The dimension of the Chow variety of curves