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We study log canonical models of foliated surfaces of general type. In particular, we show that log canonical models of general type and their minimal partial du Val resolutions are bounded. Moreover, we show the valuative criteria of…

Algebraic Geometry · Mathematics 2022-02-25 Yen-An Chen

In this paper, I prove a very general extension theorem for log pluricanonical systems. The main application of this extension theorem is (together with Kawamata's subadjunction theorem) to give an optimal subadjunction theorem which…

Algebraic Geometry · Mathematics 2007-11-05 Hajime Tsuji

We prove the normality of minimal log canonical centers on threefold pairs which residue fields are perfect of residue characteristics $p\neq 2,3 $ and $5$. We also show that the union of all log canonical centers on threefold pairs with…

Algebraic Geometry · Mathematics 2023-02-16 Emelie Arvidsson , Quentin Posva

Given a log canonical pair $(X, \Delta)$, we show that $K_X+\Delta$ is nef assuming there is no non-constant map from the affine line with values in the open strata of the stratification induced by the non-klt locus of $(X, \Delta)$. This…

Algebraic Geometry · Mathematics 2021-10-12 Roberto Svaldi

Let $\overline{\mathrm{Mov}}^k(X)$ be the closure of the cone $\mathrm{Mov}^k(X)$ generated by classes of effective divisors on a projective variety $X$ with stable base locus of codimension at least $k+1$. We propose a generalized version…

Algebraic Geometry · Mathematics 2024-05-24 Gilberto Bini , Maria Chiara Brambilla , Claudio Fontanari , 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

In this article we give two independent proofs of the positive characteristic analog of the log terminal inversion of adjunction. We show that for a pair $(X, S+B)$ in characteristic $p>0$, if $(S^n, B_{S^n})$ is strongly $F$-regular, then…

Algebraic Geometry · Mathematics 2015-04-17 Omprokash Das

We prove that a pointed one dimensional family of varieties $\mathcal{X}\to {b\in B}$ in positive characteristics is locally stable iff the log pair $(\mathcal{X'}, \mathcal{X}'_{b'})$ arising from its base change to the perfectoid base…

Algebraic Geometry · Mathematics 2020-01-14 Zhi Hu , Runhong Zong

We introduce a new technique for proving positivity of certain divisor classes on $\bar{M}_{0,n}$ and its weighted variants. Our methods give an unconditional description of the spaces of symmetric weighted pointed rational curves as log…

Algebraic Geometry · Mathematics 2011-09-16 Maksym Fedorchuk , David Ishii Smyth

We describe the foundation of the log minimal model program for log canonical pairs according to Ambro's idea. We generalize Koll\'ar's vanishing and torsion-free theorems for embedded simple normal crossing pairs. Then we prove the cone…

Algebraic Geometry · Mathematics 2009-07-10 Osamu Fujino

Given a three-dimensional projective log canonical pair over a perfect field of characteristic larger than five, there exists a minimal model program that terminates after finitely many steps.

Algebraic Geometry · Mathematics 2019-03-06 Kenta Hashizume , Yusuke Nakamura , Hiromu Tanaka

Let $(X,D)$ be an open log del Pezzo surface of rank one, that is, $X$ is a normal projective surface of Picard rank one, the boundary $D$ is a reduced nonzero divisor on $X$, and the anti-log canonical divisor $-(K_X+D)$ is ample. We show…

Algebraic Geometry · Mathematics 2025-08-20 Karol Palka , Tomasz Pełka

We prove, under suitable conditions, that there exist wall-crossing and reduction morphisms for moduli spaces of stable log pairs in all dimensions as one varies the coefficients of the divisor.

Algebraic Geometry · Mathematics 2023-01-27 Kenneth Ascher , Dori Bejleri , Giovanni Inchiostro , Zsolt Patakfalvi

We prove that the canonical ring of a smooth projective variety is finitely generated.

Algebraic Geometry · Mathematics 2008-08-14 Caucher Birkar , Paolo Cascini , Christopher D. Hacon , James McKernan

We show that the number of marked minimal models of an n-dimensional smooth complex projective variety of general type can be bounded in terms of its volume, and, if n=3, also in terms of its Betti numbers. For an n-dimensional projective…

Algebraic Geometry · Mathematics 2020-11-30 Diletta Martinelli , Stefan Schreieder , Luca Tasin

Given an ambient variety $X$ and a fixed subvariety $Z$ we give sufficient conditions for the existence of a boundary $\Delta$ such that $Z$ is a log canonical center for the pair $(X, \Delta)$. We also show that under some additional…

Algebraic Geometry · Mathematics 2015-12-02 Lorenzo Prelli

Let $f: (X,D) \to B$ be a stably family with log canonical general fiber. We prove that, after a birational modification of the base $\tilde{B} \to B$, there is a morphism from a high fibered power of the family to a pair of log general…

Algebraic Geometry · Mathematics 2016-10-05 Kenneth Ascher , Amos Turchet

We show that if $(X,B)$ is a log canonical pair with $\dim X\geq d+2$, whose non-klt centers have dimension $\geq d$, then $X$ is has depth $\ge d+2$ at every closed point.

Algebraic Geometry · Mathematics 2012-06-29 Valery Alexeev , Christopher D. Hacon

Let f: X \to Z be a surjective morphism of smooth complex projective varieties with connected fibers. Suppose that L is a pseudo-effective divisor on X that is f-numerically trivial. We show that there is a divisor D on Z such that L is…

Algebraic Geometry · Mathematics 2012-01-16 Brian Lehmann

We discuss the cone theorem for quasi-log schemes and the Mori hyperbolicity. In particular, we establish that the log canonical divisor of a Mori hyperbolic projective normal pair is nef if it is nef when restricted to the non-lc locus.…

Algebraic Geometry · Mathematics 2022-12-27 Osamu Fujino
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