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Dopo aver ricordato i principali risultati concernenti l'unirazionalità dell'ipersuperficie quartica generale $X_{4}$ di $P^{n}$ (definita su un corpo K qualsiasi) si illustra la costruzione geometrica che permette di provare l'esistenza di una superficie razionale in ogni $X_{4}$ di $P^{n}$ , con $n \geq 4$ , 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

Piotr Blass (1982)

Compositio Mathematica

Unramified cohomology and rationality problems.

Emmanuel Peyre (1993)

Mathematische Annalen

Variétés de Prym et jacobiennes intermédiaires

Arnaud Beauville (1977)

Annales scientifiques de l'École Normale Supérieure

Variétés rationnellement connexes

Olivier Debarre (2001/2002)

Séminaire Bourbaki

Variétés stablement rationnelles non rationnelles

Laurent Moret-Bailly (1984/1985)

Séminaire Bourbaki

Variétés unirationnelles non rationnelles: au-delà de l'example d'Artin et Mumford.

J.-L. Colliot-Thélène, M. Ojanguren (1989)

Inventiones mathematicae

Varieties of minimal rational tangents of codimension 1

Jun-Muk Hwang (2013)

Annales scientifiques de l'École Normale Supérieure

Let $X$ be a uniruled projective manifold and let $x$ be a general point. The main result of [2] says that if the $(- K_{X})$ -degrees (i.e., the degrees with respect to the anti-canonical bundle of $X$ ) of all rational curves through $x$ are at least $dim X + 1$ , then $X$ is a projective space. In this paper, we study the structure of $X$ when the $(- K_{X})$ -degrees of all rational curves through $x$ are at least $dim X$ . Our study uses the projective variety $𝒞_{x} \subset ℙ T_{x} (X)$ , called the VMRT at $x$ , defined as the union of tangent directions to the rational curves...

Very Ample Divisors on Rational Surfaces.

Brian Harbourne (1985)

Mathematische Annalen

Zariski surfaces [Book]

Piotr Blass (1983)

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Displaying 101 – 120 of 128

Torsion in K2 of fields and 0-cycles on rational surfaces.

Transformation Groups on Homogeneous-Rational Manifolds.

Twistor spaces with a pencil of fundamental divisors.

Über den Derivationenmodul und das Jacobi-Ideal von Kurvensingularitäten.

Ueber v. Staudt's Rechnung mit Würfen und verwandte Processe

Une conjecture pour la cohomologie des diviseurs sur les surfaces rationelles génériques.

Unirational quartic hypersurfaces