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For $\mathbb Q$-factorial klt algebraically integrable adjoint foliated structures, we prove the cone theorem, the contraction theorem, and the existence of flips. Therefore, we deduce the existence of the minimal model program for such…

Algebraic Geometry · Mathematics 2024-08-27 Paolo Cascini , Jingjun Han , Jihao Liu , Fanjun Meng , Calum Spicer , Roberto Svaldi , Lingyao Xie

We prove that if $(X, B+\mathbf{M})$ is a generalized klt pair with $K_X+B+\mathbf{M}_X$ nef and abundant, then $K_X+B+\mathbf{M}_X$ is semiample. More generally, we prove a generalized basepoint free theorem for generalized klt pairs.

Algebraic Geometry · Mathematics 2023-04-18 Priyankur Chaudhuri

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

Consider a field $k$ of characteristic $0$, not necessarily algebraically closed, and a fixed algebraic curve $f=0$ defined by a tame polynomial $f\in k[x,y]$ with only quasi-homogeneous singularities. We prove that the space of holomorphic…

Algebraic Geometry · Mathematics 2021-01-22 César Camacho , Hossein Movasati

Let $(X, \Delta)$ be a projective klt three dimensional pair defined over an algebraically closed field characteristic larger than 5. Let $L$ be a nef and big line bundle on $X$ such that $L-K_X-\Delta$ is big and nef. We show that $L$ is…

Algebraic Geometry · Mathematics 2014-03-18 Chenyang Xu

We explore the birational structure and invariants of a foliated surface $(X, \mathcal F)$ in terms of the adjoint divisor $K_{\mathcal F}+\epsilon K_X$, $0< \epsilon \ll 1$. We then establish a bound on the automorphism group of an adjoint…

Algebraic Geometry · Mathematics 2026-04-17 Calum Spicer , Roberto Svaldi

Let $(X,\Delta)$ be a proper dlt pair and $L$ a nef Cartier divisor such that $aL-(K_X+\Delta)$ is nef and log big on $(X,\Delta)$ for some $a\in {\mathbb Z}_{>0}$. Then $|mL|$ is base point free for every $m\gg 0$.

Algebraic Geometry · Mathematics 2007-05-23 Osamu Fujino

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 prove that the characteristic foliation $F$ on a non-singular divisor $D$ in an irreducible projective hyperkaehler manifold $X$ cannot be algebraic, unless the leaves of $F$ are rational curves or $X$ is a surface. More generally, we…

Algebraic Geometry · Mathematics 2016-04-18 Ekaterina Amerik , Frédéric Campana

This is the first in a series of papers about foliations in derived geometry. After introducing derived foliations on arbitrary derived stacks, we concentrate on quasi-smooth and rigid derived foliations on smooth complex algebraic…

Algebraic Geometry · Mathematics 2020-05-22 Bertrand Toën , Gabriele Vezzosi

Let $k$ be an $F$-finite field containing an infinite perfect field of positive characteristic. Let $(X, \Delta)$ be a projective log canonical pair over $k$. In this note we show that, for a semi-ample divisor $D$ on $X$, there exists an…

Algebraic Geometry · Mathematics 2017-03-21 Hiromu Tanaka

We give a classification of pairs (F, f) where F is a holomorphic foliation on a projective surface and f is a non-invertible dominant rational map preserving F. We prove that both the map and the foliation are integrable in a suitable…

Complex Variables · Mathematics 2010-03-16 C. Favre , J. Vitorio Pereira

We prove the base point free theorem for log canonical foliated pairs of rank one on a Q-factorial projective klt threefold. Moreover, we show abundance in the case of numerically trivial log canonical foliated pairs of rank one in any…

Algebraic Geometry · Mathematics 2026-01-21 Paolo Cascini , Calum Spicer

Given a canonical algebraically integrable foliation on a klt projective variety, we study the variation of the ample models of the associated adjoint foliated structures with respect to the parameter. When the foliation is of general type,…

Algebraic Geometry · Mathematics 2025-10-06 Paolo Cascini , Jihao Liu , Fanjun Meng , Roberto Svaldi , Lingyao Xie

Frobenius' theorem in differential geometry asserts that every involutive subbundle of the tangent bundle of a manifold $M$ integrates to a decomposition of $M$ into smooth leaves. We prove an infinitesimal analogue of this result for…

Algebraic Geometry · Mathematics 2025-12-09 Lukas Brantner , Kirill Magidson , Joost Nuiten

Let $X$ be a $\mathbb Q$-Fano variety admitting a K\"ahler-Einstein metric. We prove that up to a finite quasi-\'etale cover, $X$ splits isometrically as a product of K\"ahler-Einstein $\mathbb Q$-Fano varieties whose tangent sheaf is…

Algebraic Geometry · Mathematics 2020-08-13 Stéphane Druel , Henri Guenancia , Mihai Păun

This paper demonstrates the existence of $\mathbb{Q}$-complements for algebraically integrable log-Fano foliations on klt ambient varieties. Additionally, we investigate properties of algebraically integrable Fano foliations such as a…

Algebraic Geometry · Mathematics 2024-08-22 Yen-An Chen , Dongchen Jiao , Pascale Voegtli

In this paper, we prove that an algebraic fiber space $f:X\to Y$ over a perfect field $k$ of characteristic $p>0$ with nef relative anti-canonical divisor $-K_{X/Y}$ splits into the product after taking the base change along a finite cover…

Algebraic Geometry · Mathematics 2023-08-30 Sho Ejiri

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 first provide details for the proof of Fujita's second theorem for K\"ahler fibre spaces over a curve, asserting that the direct image $V$ of the relative dualizing sheaf splits as the direct sum $ V = A \oplus Q$, where $A$ is ample and…

Algebraic Geometry · Mathematics 2013-11-14 Fabrizio Catanese , Michael Dettweiler
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