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The goal of these lectures is to explain speaker’s results on uniqueness properties of spherical varieties. By a uniqueness property we mean the following. Consider some special class of spherical varieties. Define some combinatorial invariants for spherical varieties from this class. The problem is to determine whether this set of invariants specifies a spherical variety in this class uniquely (up to an isomorphism). We are interested in three classes: smooth affine varieties, general affine varieties,...

Unirational quartic hypersurfaces

Marina Rosanna Marchisio (2000)

Bollettino dell'Unione Matematica Italiana

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

Universal transitivity of simple and 2-simple prehomogeneous vector spaces

T. Kimura, S. Kasai, H. Hosokawa (1988)

Annales de l'institut Fourier

We denote by $k$ a field of characteristic zero satisfying $H^{1} (k, Aut (S L_{2})) \neq 0$ . Let $G$ be a connected $k$ -split linear algebraic group acting on $X = {Aff}^{n}$ rationally by $ρ$ with a Zariski-dense $G$ -orbit $Y$ . A prehomogeneous vector space $(G, ρ$ ,X) is called “universally transitive” if the set of $k$ -rational points $Y (k)$ is a single $ρ$ $(G) ...$

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Une remarque sur les générateurs du cobordisme complexe.

Une résolution en singularités toriques simpliciales des singularités-quotient de dimension trois

Une théorie de l'intersection dans un espace singulier

Uniform bound for generic points of curves in tori.

Uniformizing differential equations of several Hilbert modular orbifolds.

Uniqueness properties for spherical varieties

Unirational quartic hypersurfaces

Unirationality of Enriques surfaces in characteristic two

Universal transitivity of simple and 2-simple prehomogeneous vector spaces

Unramified cohomology and rationality problems.

Unramified cohomology of classifying varieties for classical simply connected groups

Upper Bounds for the Degrees of the Equations Defining Locally Cohen-Macaulay Schemes.

Currently displaying 21 – 32 of 32