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Sur toute surface de del Pezzo de degr\'e 4 sur un corps $C_1$ de caract\'eristique z\'ero, tous les points rationnels sont R-\'equivalents. Plus g\'en\'eralement, ceci vaut sur tout corps parfait infini de caract\'eristique diff\'erente de…

Algebraic Geometry · Mathematics 2015-09-22 Jean-Louis Colliot-Thélène

We construct the first examples of regular del Pezzo surfaces for which the irregularity (i.e. the dimension of the first cohomology group of the structure sheaf) is nonzero. We also find a restriction on the integer pairs that are possible…

Algebraic Geometry · Mathematics 2013-04-23 Zachary Maddock

We prove that very general non-rational Fano threefolds which are not birational to cubic threefolds are not stably rational.

Algebraic Geometry · Mathematics 2016-01-27 Brendan Hassett , Yuri Tschinkel

If a smooth, geometrically rational surface over a finite field is not rational over that field, then over some finite extension of that field the Brauer group of the surface is nonzero. In particular such a surface is not stably rational.…

Algebraic Geometry · Mathematics 2018-06-19 Jean-Louis Colliot-Thélène

In an algebro-geometric way, we completely determine whether smooth del Pezzo surfaces are K-(semi)stable or not.

Algebraic Geometry · Mathematics 2019-03-25 Jihun Park , Joonyeong Won

We study the rationality of some geometrically rational three-dimensional conic and quadric surface bundles, defined over the reals and more general real closed fields, for which the real locus is connected and the intermediate Jacobian…

Algebraic Geometry · Mathematics 2026-04-22 Olivier Benoist , Alena Pirutka

Let $X$ be a del Pezzo surface of degree $2$ or greater over a finite field $\mathbb{F}_q$. The image $\Gamma$ of the Galois group $\operatorname{Gal}(\overline{\mathbb{F}}_q / \mathbb{F}_q)$ in the group…

Algebraic Geometry · Mathematics 2018-03-21 Andrey Trepalin

Let $k$ be an infinite field of characteristic 0, and $X$ a del Pezzo surface of degree $d$ with at least one $k$-rational point. Various methods from algebraic geometry and arithmetic statistics have shown the Zariski density of the set…

Algebraic Geometry · Mathematics 2022-06-30 Julie Desjardins , Rosa Winter

Let $X$ be a minimal del Pezzo surface of degree $2$ over a finite field $\mathbb{F}_q$. The image $\Gamma$ of the Galois group $\operatorname{Gal}(\overline{\mathbb{F}}_q / \mathbb{F}_q)$ in the group…

Algebraic Geometry · Mathematics 2017-09-08 Andrey Trepalin

In this paper we study the semi-stable reduction of Galois covers of degree p above semi-stable curves over a complete discrete valuation ring of inequal characteristics (0,p). We are also able to describe the Galois action on these covers…

Algebraic Geometry · Mathematics 2007-05-23 Mohamed Saidi

We compute the coregularity of del Pezzo surfaces with du Val singularities. To this aim, we study the relation between del Pezzo surfaces of degree $1$ and elliptic fibrations. It turns out that del Pezzo surfaces with positive…

Algebraic Geometry · Mathematics 2026-03-04 Konstantin Loginov , Andrey Trepalin

The aim of the paper is to construct examples of cyclic covers of $CP^m\times CP^n$ which are rationally connected but are not rational. The crucial point turns out to be the study of Del Pezzo surfaces over function fields in positive…

alg-geom · Mathematics 2008-02-03 János Kollár

In this article, we give the classification of normal del Pezzo surfaces of rank one with at most log canonical singularities containing the affine plane defined over an algebraically non-closed field of characteristic zero. As an…

Algebraic Geometry · Mathematics 2023-03-24 Masatomo Sawahara

We construct absolutely simple jacobians of non-hyperelliptic genus 4 curves, using Del Pezzo surfaces of degree 1. This paper is a natural continuation of author's paper math.AG/0405156.

Algebraic Geometry · Mathematics 2024-08-05 Yuri G. Zarhin

We address weak approximation for certain del Pezzo surfaces defined over the function field of a curve. We study the rational connectivity of the smooth locus of degree two del Pezzo surfaces with two A1 singularities in order to prove…

Algebraic Geometry · Mathematics 2008-09-09 Amanda Knecht

We exhibit new examples of rational cubic fourfolds, parametrized by a countably infinite union of codimension-two subvarieties in the moduli space. Our examples are fibered in sextic del Pezzo surfaces over the projective plane; they are…

Algebraic Geometry · Mathematics 2020-12-17 Nicolas Addington , Brendan Hassett , Yuri Tschinkel , Anthony Várilly-Alvarado

We classify all generalized del Pezzo surfaces (i.e., minimal desingularizations of singular del Pezzo surfaces containing only rational double points) whose universal torsors are open subsets of hypersurfaces in affine space. Equivalently,…

Algebraic Geometry · Mathematics 2014-02-26 Ulrich Derenthal

We establish a couple of dynamical properties of surjective rational maps $f: X \dashrightarrow X$ for smooth projective surfaces $X$. We also give a numerical characterization of regular $f$ in the case when $X$ is a del Pezzo surface.…

Algebraic Geometry · Mathematics 2026-03-26 Ilya Karzhemanov

We completely solve the inverse Galois problem for del Pezzo surfaces of degree $2$ and $3$ over all finite fields.

Algebraic Geometry · Mathematics 2019-02-25 Daniel Loughran , Andrey Trepalin

We describe smooth rational projective algebraic surfaces over an algebraically closed field of characteristic different from 2 which contain $n \ge \b_2-2$ disjoint smooth rational curves with self-intersection -2, where $\b_2$ is the…

Algebraic Geometry · Mathematics 2007-05-23 Igor Dolgachev , Margarida Mendes Lopes , Rita Pardini
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