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Related papers: Log canonical pairs with good augmented base loci

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In this paper, we prove that given a flat generically smooth morphism between smooth projective varieties with $F$-pure closed fibers, if the source space is Fano, weak Fano or a variety with the nef anti-canonical divisor, then so is the…

Algebraic Geometry · Mathematics 2019-12-11 Sho Ejiri

For every $d \geq 4$, we construct a $d$-dimensional, log canonical, $K$-trivial variety with the property that two general fibers of its Albanese morphism are not birational. This provides a strong counterexample to the…

Algebraic Geometry · Mathematics 2026-05-11 Fabio Bernasconi , Stefano Filipazzi , Zsolt Patakfalvi , Nikolaos Tsakanikas

For smooth projective 3-folds of general type, we prove that the relative canonical stability $\mu_s(3)\leq 8$. This is induced from our improved result of Koll\'ar: the m-canonical map of a smooth projective 3-fold of general type is…

Algebraic Geometry · Mathematics 2007-05-23 Meng Chen

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

Let X be a projective variety which is algebraic Lang hyperbolic. We show that Lang's conjecture holds (one direction only): X and all its subvarieties are of general type and the canonical divisor K_X is ample at smooth points and Kawamata…

Algebraic Geometry · Mathematics 2019-07-08 Fei Hu , Sheng Meng , De-Qi Zhang

We consider the union of certain irreducible components of cohomological support loci of the canonical bundle, which we call standard. We prove a structure theorem about them and single out some particular cases, recovering and improving…

Algebraic Geometry · Mathematics 2016-10-17 Giuseppe Pareschi

We introduce the notion of quasi-log complex analytic spaces and establish various fundamental properties. Moreover, we prove that a semi-log canonical pair naturally has a quasi-log complex analytic space structure. This paper is part of…

Algebraic Geometry · Mathematics 2025-02-04 Osamu Fujino

We develop a theory of $P$-trivial MMP whose each step is $P$-trivial for a given nef divisor $P$. As an application, we prove that, given a projective generalised klt pair $(X,B+M)$ with data $M'$ being just a nef $\mathbb{R}$-divisor, if…

Algebraic Geometry · Mathematics 2025-01-14 Zhengyu Hu

We classify minimal pairs (X, G) for smooth rational projective surface X and finite group G of automorphisms on X. We also determine the fixed locus X^G and the quotient surface Y = X/G as well as the fundamental group of the smooth part…

Algebraic Geometry · Mathematics 2007-05-23 D. -Q. Zhang

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

Semi-log canonical varieties are a higher-dimensional analogue of stable curves. They are the varieties appearing as the boundary $\Delta$ of a log canonical pair $(X,\Delta)$, and also appear as limits of canonically polarized varieties in…

Algebraic Geometry · Mathematics 2019-08-14 Morgan V Brown

In this paper, we study the singularities of a pair (X,Y) in arbitrary characteristic via jet schemes. For a smooth variety X in characteristic 0, Ein, Lazarsfeld and Mustata showed that there is a correspondence between irreducible closed…

Algebraic Geometry · Mathematics 2013-08-27 Zhixian Zhu

Given a normal surface singularity $(X, Q)$ and a birational morphism to a non- singular surface $\pi : X \to S$, we investigate the local geometry of the exceptional divisor $L$ of $\pi$. We prove that the dimension of the tangent space to…

Algebraic Geometry · Mathematics 2008-04-28 Jesus Fernandez-Sanchez

We consider a smooth projective surjective morphism between smooth complex projective varieties. We give a Hodge theoretic proof of the following well-known fact: If the anti-canonical divisor of the source space is nef, then so is the…

Algebraic Geometry · Mathematics 2012-01-06 Osamu Fujino , Yoshinori Gongyo

Let $(X,\Delta)$ be a 4-dimensional log variety which is proper over the field of complex numbers and with only divisorial log terminal singularities. The log canonical divisor $K_X+\Delta$ is semi-ample, if it is nef (numerically…

Algebraic Geometry · Mathematics 2007-05-23 Shigetaka Fukuda

We generalize the rationality theorem of the accumulation points of log canonical thresholds which was proved by Hacon, M\textsuperscript{c}Kernan, and Xu. Further, we apply the rationality to the ACC problem on the minimal log…

Algebraic Geometry · Mathematics 2024-04-30 Yusuke Nakamura

We prove an effective vanishing theorem for direct images of log pluricanonical bundles of projective semi-log canonical pairs. As an application, we obtain a semipositivity theorem for direct images of relative log pluricanonical bundles…

Algebraic Geometry · Mathematics 2018-02-16 Osamu Fujino

We prove the finiteness of $B$-representations of generalised log canonical pairs. As a consequence, we prove that, the (relative) abundance for a generalised semi-log canonical pair is implied by the abundance for its normalisation.…

Algebraic Geometry · Mathematics 2021-03-23 Zhengyu Hu

Let $(X, \Delta)$ be a four-dimensional log variety that is projective over the field of complex numbers. Assume that $(X, \Delta)$ is not Kawamata log terminal (klt) but divisorial log terminal (dlt). First we introduce the notion of "log…

Algebraic Geometry · Mathematics 2007-05-23 Shigetaka Fukuda

We prove the abundance theorem for numerically trivial log canonical divisors of log canonical pairs and semi-log canonical pairs.

Algebraic Geometry · Mathematics 2010-09-14 Yoshinori Gongyo