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We study zero cycles on rationally connected varieties defined over characteristic zero Laurent fields with algebraically closed residue fields. We show that the degree map induces an isomorphism for rationally connected threefolds defined…

Algebraic Geometry · Mathematics 2020-10-13 Zhiyu Tian

We give upper and lower bounds for the number of rational points on Prym varieties over finite fields. Moreover, we determine the exact maximum and minimum number of rational points on Prym varieties of dimension 2.

Algebraic Geometry · Mathematics 2013-07-15 Yves Aubry , Safia Haloui

The goal of this article is to study the equations and syzygies of embeddings of rational surfaces and certain Fano varieties. Given a rational surface X and an ample and base-point-free line bundle L on X, we give an optimal numerical…

Algebraic Geometry · Mathematics 2007-05-23 Francisco Javier Gallego , B. P. Purnaprajna

The aim of this note is to settle some foundational questions about the behavior of birational rigidity in extensions of algebraically closed fields.

Algebraic Geometry · Mathematics 2008-09-08 János Kollár

This is a report on some of the main developments in birational geometry in the last few years focusing on the minimal model program, Fano varieties, singularities and related topics, in characteristic zero.

Algebraic Geometry · Mathematics 2018-01-03 Caucher Birkar

We study a particular class of rationally connected manifolds, $X\subset \p^N$, such that two general points $x,x' \in X$ may be joined by a conic contained in $X$. We prove that these manifolds are Fano, with $b_2\leq 2$. Moreover, a…

Algebraic Geometry · Mathematics 2012-09-11 Paltin Ionescu , Francesco Russo

We study the rationality of the intersection points of certain lines and smooth plane quartics C defined over F_q. For q \geq 127, we prove the existence of a line such that the intersection points with C are all rational. Using another…

Number Theory · Mathematics 2010-07-07 Roger Oyono , Christophe Ritzenthaler

We describe the set of Mori structures for a Fano 3-fold of index 2 and degree 1 (the double cone over the Veronese surface). In partiular, it is proved that such a Fano variety is not rational, the group of birational automorphisms…

Algebraic Geometry · Mathematics 2007-05-23 Mikhail Grinenko

The goal of this work is to study geometric properties of geometrically irreducible subschemes on degenerations of Fano varieties (more generally, of separably rationally connected varieties). It is known that these geometrically…

Algebraic Geometry · Mathematics 2024-09-17 Santai Qu

We prove the birational rigidity of Fano complete intersections of index 1 with a singular point of high multiplicity, which can be close to the degree of the variety. In particular, the groups of birational and biregular automorphisms of…

Algebraic Geometry · Mathematics 2017-11-07 Aleksandr V. Pukhlikov

We develop a sequential-topological study of rational points of schemes of finite type over local rings typical in higher dimensional number theory and algebraic geometry. These rings are certain types of multidimensional complete fields…

Algebraic Geometry · Mathematics 2012-03-02 Alberto Camara

In this paper, we give an affirmative answer to a conjecture in the Minimal Model Program. We prove that log $Q$-Fano varieties of dim $n$ are rationally connected. We also study the behavior of the canonical bundles under projective…

Algebraic Geometry · Mathematics 2007-05-23 Qi Zhang

We find a relation between a cubic hypersurface $Y$ and its Fano variety of lines $F(Y)$ in the Grothendieck ring of varieties. We prove that if the class of an affine line is not a zero-divisor in the Grothendieck ring of varieties, then…

Algebraic Geometry · Mathematics 2014-06-27 Sergey Galkin , Evgeny Shinder

In this note, we reduce various conjectures in birational geometry, including Shokurov conjecture on singularities of the base of log Calabi-Yau fibrations of Fano type and boundedness conjecture for rationally connected Calabi-Yau…

Algebraic Geometry · Mathematics 2026-03-16 Guodu Chen , Chuyu Zhou

Various methods have been used to construct rational points and rational curves on rationally connected algebraic varieties. We survey recent advances in two of them, the descent and the fibration method, in a number-theoretical context…

Algebraic Geometry · Mathematics 2023-12-27 Olivier Wittenberg

We give some bounds on the numbers of rational points on abelian varieties and jacobians varieties over finite fields. The main result is that we determine the maximum and minimum number of rational points on jacobians varieties of…

Algebraic Geometry · Mathematics 2010-02-22 Safia Haloui

We show that for a Zariski general hypersurface $V$ of degree $M+1$ in ${\mathbb P}^{M+1}$ for $M\geqslant 5$ there are no Galois rational covers $X\dashrightarrow V$ of degree $d\geqslant 2$ with an abelian Galois group, where $X$ is a…

Algebraic Geometry · Mathematics 2024-04-17 Aleksandr V. Pukhlikov

This paper proposes the use of $F$-split and globally $F$-regular conditions in the pursuit of BAB type results in positive characteristic. The main technical work comes in the form of a detailed study of threefold Mori fibre spaces over…

Algebraic Geometry · Mathematics 2023-02-07 Liam Stigant

Using deformation theory of rational curves, we prove a conjecture of Sommese on the extendability of morphisms from ample subvarieties when the morphism is a smooth (or mildly singular) fibration with rationally connected fibers. We apply…

Algebraic Geometry · Mathematics 2020-11-23 Tommaso de Fernex , Chung Ching Lau

We study the spaces of rational curves on Fano threefolds with Gorenstein terminal singularities. We generalize the results regarding Geometric Manin's Conjecture for smooth Fano threefolds, including the classification of subvarieties with…

Algebraic Geometry · Mathematics 2025-05-23 Fumiya Okamura