English
Related papers

Related papers: The augmented base locus of real divisors over arb…

200 papers

Let $f:X \to S$ be a projective morphism of noetherian schemes and let $L$ be an invertible sheaf on $X$. We show that the relative augmented base locus of $L$ coincides with the relative exceptional locus of $L$. We also prove a…

Algebraic Geometry · Mathematics 2023-08-08 Yusuke Ushiro

Let $L$ be a nef and big line bundle on a scheme $X$. It is well known that if $X$ is a projective over a field then the augmented base locus and the exceptional base locus agree. This result is extended to projective schemes over arbitrary…

Algebraic Geometry · Mathematics 2023-02-07 Liam Stigant

Let L be a nef line bundle on a projective scheme X in positive characteristic. We prove that the augmented base locus of L is equal to the union of the irreducible closed subsets V of X such that the restriction of L to V is not big. For a…

Algebraic Geometry · Mathematics 2012-01-20 Paolo Cascini , James McKernan , Mircea Mustata

We prove that the non-nef locus and the restricted base locus of a pseudoeffective divisor coincide on KLT pairs. We also extend to KLT pairs F. Russo's characterization of nef and abundant divisors by means of asymptotic multiplier ideals.

Algebraic Geometry · Mathematics 2012-10-19 Salvatore Cacciola , Lorenzo Di Biagio

We generalize Nakamaye's description, via intersection theory, of the augmented base locus of a big and nef divisor on a normal pair with log-canonical singularities or, more generally, on a normal variety with non-lc locus of dimension at…

Algebraic Geometry · Mathematics 2014-12-24 Salvatore Cacciola , Angelo Felice Lopez

Let $(X,B)$ be a projective log canonical pair such that $B$ is a $\Q$-divisor, and that there is a surjective morphism $f\colon X\to Z$ onto a normal variety $Z$ satisfying: $K_X+B\sim_\Q f^*M$ for some $\Q$-divisor $M$, and the augmented…

Algebraic Geometry · Mathematics 2019-02-20 Caucher Birkar , Zhengyu Hu

We prove that the asymptotic base loci of an NQC klt generalized pair with big canonical class are uniruled. We also show that the non-nef locus and the diminished base locus of the adjoint divisor of an NQC log canonical generalized pair…

Algebraic Geometry · Mathematics 2024-04-26 Nikolaos Tsakanikas , Zhixin Xie

We extend to normal projective varieties defined over an arbitrary algebraically closed field a result of Ein, Lazarsfeld, Musta\c{t}\u{a}, Nakamaye and Popa characterizing the augmented base locus (aka non-ample locus) of a line bundle on…

Algebraic Geometry · Mathematics 2014-12-24 Sébastien Boucksom , Salvatore Cacciola , Angelo Felice Lopez

We study the cone of Moriwaki divisors on \bar{M}_g by means of augmented base loci. Using a result of Moriwaki, we prove that an R-divisor D satisfies the strict Moriwaki inequalities if and only if the augmented base locus of D is…

Algebraic Geometry · Mathematics 2016-09-07 Salvatore Cacciola , Angelo Felice Lopez , Filippo Viviani

We present a new class of examples of base points for the generalized theta divisor on the moduli space of semistable vector bundles of trivial determinant on a compact Riemann surface and we prove that for sufficiently large rank the base…

Algebraic Geometry · Mathematics 2009-10-31 Mihnea Popa

We study the pullback of the stable and augmented base locus under a finite surjective morphism between normal varieties over a perfect field.

Algebraic Geometry · Mathematics 2022-09-19 Tanuj Gomez

Let $X$ be a complete algebraic variety over {\bf C}. We consider a log variety $(X,\Delta)$ that is weakly Kawamata log terminal. We assume that $K_X+\Delta$ is a {\bf Q}-Cartier {\bf Q}-divisor and that every irreducible component of…

Algebraic Geometry · Mathematics 2007-05-23 Shigetaka Fukuda

We construct log resolutions of pairs on the blow-up of the projective space in an arbitrary number of general points and we discuss the semi-ampleness of the strict transforms. As an application we prove that the abundance conjecture holds…

Algebraic Geometry · Mathematics 2019-04-08 Olivia Dumitrescu , Elisa Postinghel

Given a projective hyper-K\"ahler manifold $X$, we study the asymptotic base loci of big divisors on $X$. We provide a numerical characterization of these loci and study how they vary while moving a big divisor class in the big cone, using…

Algebraic Geometry · Mathematics 2024-06-27 Francesco Antonio Denisi , Ángel David Ríos Ortiz

We introduce and study the restricted volume of a divisor along a subvariety. Our main result is a description of the irreducible components of the augmented base locus by the vanishing of the restricted volume.

Algebraic Geometry · Mathematics 2008-01-10 Lawrence Ein , Robert Lazarsfeld , Mircea Mustata , Michael Nakamaye , Mihnea Popa

We prove a base point free theorem for nef and log big divisors on log canonical surfaces.

alg-geom · Mathematics 2008-02-03 Shigetaka Fukuda

In this article we present a refinement of the base point free theorem for threefolds in positive characteristic. If $L$ is a nef Cartier divisor of numerical dimension at least one on a projective Kawamata log terminal threefold…

Algebraic Geometry · Mathematics 2020-03-17 Fabio Bernasconi

We show that the Nakai--Moishezon ampleness criterion holds for real line bundles on complete schemes. As applications, we treat the relative Nakai--Moishezon ampleness criterion for real line bundles and the Nakai--Moishezon ampleness…

Algebraic Geometry · Mathematics 2021-01-05 Osamu Fujino , Keisuke Miyamoto

We develop techniques of mimicking the Frobenius action in the study of universal homeomorphisms in mixed characteristic. As a consequence, we show a mixed characteristic Keel's base point free theorem obtaining applications towards the…

Algebraic Geometry · Mathematics 2022-01-25 Jakub Witaszek

Let $X$ be a normal projective variety defined over an algebraically closed field and let $Z$ be a subvariety. Let $D$ be an $\mathbb R$-Cartier $\mathbb R$-divisor on $X$. Given an expression $(\ast) \ D \sim_{\mathbb R} t_1 H_1 + \ldots +…

Algebraic Geometry · Mathematics 2015-10-28 Angelo Felice Lopez
‹ Prev 1 2 3 10 Next ›