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We prove the following results for projective klt pairs of dimension $3$ over an algebraically closed field of char $p>5$: the cone theorem, the base point free theorem, the contraction theorem, finiteness of minimal models, termination…

Algebraic Geometry · Mathematics 2014-10-17 Caucher Birkar , Joe Waldron

We prove that many of the results of the LMMP hold for $3$-folds over fields of characteristic $p>5$ which are not necessarily perfect. In particular, the existence of flips, the cone theorem, the contraction theorem for birational extremal…

Algebraic Geometry · Mathematics 2022-08-22 Omprokash Das , Joe Waldron

We prove existence of flips, special termination, the base point free theorem and, in the case of log general type, the existence of minimal models for F-dlt foliated pairs of co-rank one on a $\mathbb Q$-factorial projective threefold. As…

Algebraic Geometry · Mathematics 2025-09-05 Paolo Cascini , Calum Spicer

We show that minimal models of $\mathbb{Q}$-factorial NQC log canonical generalised pairs exist, assuming the existence of minimal models of smooth varieties. More generally, we prove that on a $\mathbb{Q}$-factorial NQC log canonical…

Algebraic Geometry · Mathematics 2022-12-19 Vladimir Lazić , Nikolaos Tsakanikas , with an appendix joint with Xiaowei Jiang

We use the theory of foliations to study the relative canonical divisor of a normalized inseparable base-change. Our main technical theorem states that it is linearly equivalent to a divisor with positive integer coefficients divisible by…

Algebraic Geometry · Mathematics 2018-08-28 Zsolt Patakfalvi , Joe Waldron

If $(X, \mcF, \D)$ is a projective rank two foliated log canonical triple such that $(X,B)$ is klt for some $0 \leq B \leq \D$, we show that we can run a $(K_\mcF +\Delta)$-MMP and any such MMP terminates with either a minimal model or Mori…

Algebraic Geometry · Mathematics 2025-12-23 Priyankur Chaudhuri , Roktim Mascharak

We discuss the birational geometry of singular surfaces in positive characteristic. More precisely, we establish the minimal model program and the abundance theorem for Q-factorial surfaces and for log canonical surfaces. Moreover, in the…

Algebraic Geometry · Mathematics 2015-03-17 Hiromu Tanaka

We settle a question that originates from results and remarks by Koll\'ar on extremal ray in the minimal model program: In positive characteristics, there are no Mori fibrations on threefolds with only terminal singularities whose generic…

Algebraic Geometry · Mathematics 2021-10-04 Andrea Fanelli , Stefan Schröer

The first aim of this note is to give a concise, but complete and self-contained, presentation of the fundamental theorems of Mori theory - the nonvanishing, base point free, rationality and cone theorems - using modern methods of…

Algebraic Geometry · Mathematics 2014-02-26 Alessio Corti , Anne-Sophie Kaloghiros , Vladimir Lazic

For lc algebraically integrable foliations on klt varieties, we prove the base-point-freeness theorem, the contraction theorem, and the existence of flips. The first result resolves a conjecture of Cascini and Spicer, while the latter two…

Algebraic Geometry · Mathematics 2025-06-09 Jihao Liu , Fanjun Meng , Lingyao Xie

Let $f:(X,B)\to Z$ be a 3-fold extremal dlt flipping contraction defined over an algebraically closed field of characteristic $p>5$, such that the coefficients of $\{B\}$ are in the standard set $\{1-\frac 1n|n\in \mathbb N\}$, then the…

Algebraic Geometry · Mathematics 2013-06-28 Christopher D. Hacon , Chenyang Xu

We provide several applications of the minimal model program to the local and global study of co-rank one foliations on threefolds. Locally, we prove a singular variant of Malgrange's theorem, a classification of terminal foliation…

Algebraic Geometry · Mathematics 2022-11-08 Calum Spicer , Roberto Svaldi

We survey recent progress on the birational geometry of foliations on complex varieties. We focus on the MMP viewpoint: singularities, adjunction and applications to the MMP for foliations on surfaces and to the existence of flips on…

Algebraic Geometry · Mathematics 2026-04-13 Paolo Cascini , Calum Spicer

We present an extension of several results on pairs and varieties to foliated surface pairs. We prove the boundedness of local complements, the local index theorem, and the uniform boundedness of minimal log discrepancies (mlds), as well as…

Algebraic Geometry · Mathematics 2024-06-07 Jihao Liu , Fanjun Meng , Lingyao Xie

This paper resolves several outstanding questions regarding the Minimal Model Program for klt threefolds in mixed characteristic. Namely termination for pairs which are not pseudo-effective, finiteness of minimal models and the Sarkisov…

Algebraic Geometry · Mathematics 2024-02-21 Liam Stigant

We establish the minimal model program (MMP) for generalized foliated threefolds $(X, \mathcal{F}, B, \mathbf{M})$ of rank 1, extending the result of Cascini and Spicer in [CS25d]. As an application of the generalized foliated MMP, we prove…

Algebraic Geometry · Mathematics 2025-11-21 Mengchu Li

I give a necessary and sufficient condition for a nef and big line bundle in positive characteristic to be semi-ample, and then give two applications: I show that the relative dualizing sheaf of the universal curve is semi-ample, in…

alg-geom · Mathematics 2008-02-03 Sean Keel

In this paper we prove that certain linear systems (and all their multiples) of plane curves with general base points and zero--self intersection are empty, thus exhibiting further examples of rays at the boundary of the Mori cone of a…

Algebraic Geometry · Mathematics 2021-11-05 Ciro Ciliberto , Rick Miranda

We give explicit blowups of the projective plane in positive characteristic that contain smooth rational curves of arbitrarily negative self-intersection, showing that the Bounded Negativity Conjecture fails even for rational surfaces in…

Algebraic Geometry · Mathematics 2021-03-04 Raymond Cheng , Remy van Dobben de Bruyn

In this paper, we discuss a proof of existence of log minimal models or Mori fibre spaces for klt pairs $(X/Z,B)$ with $B$ big$/Z$. This then implies existence of klt log flips, finite generation of klt log canonical rings, and most of the…

Algebraic Geometry · Mathematics 2009-04-21 Caucher Birkar , Mihai Paun
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