Une propriété des surfaces rationnelles
Une résolution en singularités toriques simpliciales des singularités-quotient de dimension trois
Une sextique de l'espace projectif réel avec un grand nombre d'anses.
It follows from the known restrictions on the topology of a real algebraic variety that the number of handles of the real part of a real nonsingular sextic in CP3 is at most 47. We construct a real nonsingular sextic X6 in CP3 whose real part RX6 has 44 handles. In particular, this surface verifies b1(RX6) = h1,1(X6) + 2. We extend the construction in order to obtain for any even m ≥ 6 a real nonsingular surface Xm of degree m in CP3 verifying b1(RXm) > h1,1(Xm). It is known that such a surface...
Une variété de dimension 4 avec forme d'intersection paire et signature - 8.
Une version géométrique généralisée du théorème du produit de Nadel
Unirational quartic hypersurfaces
Dopo aver ricordato i principali risultati concernenti l'unirazionalità dell'ipersuperficie quartica generale di (definita su un corpo K qualsiasi) si illustra la costruzione geometrica che permette di provare l'esistenza di una superficie razionale in ogni di , con , e di trovare altri esempi di ipersuperficie quartiche lisce che sono unirazionali oltre a quello dato da B. Segre nel 1960. Si mostra poi come l'analisi delle superficie quartiche monoidali (cioè contenenti un punto triplo...
Unirationality of Enriques surfaces in characteristic two
Unisecant curves on a general ruled surface.
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Unstable vector bundles and linear systems on surfaces in characteristic p.
Untersuchungen über das Flächennetz zweiter Ordnung.
Van Geemen's Families of lines on special quintic threefolds.
Vanishing cycles, the generalized Hodge Conjecture and Gröbner bases
Let X be a general complete intersection of a given multi-degree in a complex projective space. Suppose that the anti-canonical line bundle of X is ample. Using the cylinder homomorphism associated with the family of complete intersections of a smaller multi-degree contained in X, we prove that the vanishing cycles in the middle homology group of X are represented by topological cycles whose support is contained in a proper Zariski closed subset T of X with certain codimension. In some cases, by...
Vanishing of sections of vector bundles on 0-dimensional schemes
Here we give conditions and examples for the surjectivity or injectivity of the restriction map , where is a projective variety, is a vector bundle on and is a “general” -dimensional subscheme of , union of general “fat points”.
Vanishing Theorems for Resolutions of Surfaces Singularities.
Variation of moduli spaces and Donaldson invariants under change of polarization.
Variation of the canonical height on elliptic surfaces I: Three examples.
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