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We use birational geometry to show that the existence of rational points on proper rationally connected varieties over fields of characteristic $0$ is a consequence of the existence of rational points on terminal Fano varieties. We discuss…

Algebraic Geometry · Mathematics 2021-08-06 Marta Pieropan

This paper stresses the strong link between the existence of partial holomorphic connections on the normal bundle of a foliation seen as a quotient of the ambient tangent bundle and the extendability of a foliation to an infinitesimal…

Complex Variables · Mathematics 2015-01-14 Isaia Nisoli

We identify a class of singular algebraic foliations whose leaves through singular points retain regularity. The proof consists in showing existence of residual gerbes for certain formal stacks, which do not enjoy smooth presentations. As…

Algebraic Geometry · Mathematics 2025-10-24 Federico Bongiorno

In this short note we prove that in many cases the failure of a variety to be separably rationally connected is caused by the instability of the tangent sheaf (if there are no other obvious reasons). A simple application of the results…

Algebraic Geometry · Mathematics 2014-07-30 Zhiyu Tian

This work establishes a structure theorem for compact K\"ahler manifolds with semipositive anticanonical bundle. Up to finite \'etale cover, it is proved that such manifolds split holomorphically and isometrically as a product of Ricci flat…

Algebraic Geometry · Mathematics 2018-02-06 Frédéric Campana , Jean-Pierre Demailly , Thomas Peternell

We prove the bigness of the Chow-Mumford line bundle associated to a $\mathbb{Q}$-Gorenstein family of log Fano varieties of maximal variation with uniformly K-stable general geometric fibers. This result generalizes a recent theorem of…

Algebraic Geometry · Mathematics 2022-01-03 Quentin Posva

Deformation of morphisms along leaves of foliations define the tangential foliation on the corresponding space of morphisms. We prove that codimension one fo-liations having a tangential foliation with at least one non-algebraic leaf are…

Classical Analysis and ODEs · Mathematics 2021-02-23 Frank Loray , Jorge Pereira , Frédéric Touzet

In this talk, I report on three theorems concerning algebraic varieties over a field of characteristic $p>0$. a) over a finite field of cardinal $q$, two proper smooth varieties which are geometrically birational have the same number of…

Algebraic Geometry · Mathematics 2010-04-26 Antoine Chambert-Loir

We show that the singular holomorphic foliations induced by dominant quasi-homogeneous rational maps fill out irreducible components of the space $\mathscr F_q(r, d)$ of singular foliations of codimension $q$ and degree $d$ on the complex…

Algebraic Geometry · Mathematics 2010-04-05 F. Cukierman , J. V. Pereira , I. Vainsencher

In this note we study properties of partially ample line bundles on simplicial projective toric varieties. We prove that the cone of q-ample line bundles is a union of rational polyhedral cones, and calculate these cones in examples. We…

Algebraic Geometry · Mathematics 2014-09-29 Nathan Broomhead , John Christian Ottem , Artie Prendergast-Smith

In this paper, we study almost nef regular foliations. We give a structure theorem of a smooth projective variety $X$ with an almost nef regular foliation $\mathcal{F}$: $X$ admits a smooth morphism $f: X \rightarrow Y$ with rationally…

Algebraic Geometry · Mathematics 2021-03-17 Masataka Iwai

We show that if a stable variety (in the sense of Koll\'ar and Shepherd-Barron) admits a fibration with stable fibers and base, then this fibration structure deforms (uniquely) for all small deformations. During our proof we obtain also a…

Algebraic Geometry · Mathematics 2014-02-05 Zsolt Patakfalvi

We pose some questions about spaces parametrizing rational curves on rationally connected varieties. We give a partial answer for cubic threefolds. Many of our results were previously proved by Iliev, Markushevich and Tikhimirov by…

Algebraic Geometry · Mathematics 2007-05-23 Joe Harris , Mike Roth , Jason Starr

We define a notion of connection in a fibre bundle that is compatible with a singular foliation of the base. Fibre bundles equipped with such connections are in plentiful supply, arising naturally for any Lie groupoid-equivariant bundle,…

Differential Geometry · Mathematics 2021-04-29 Lachlan Ewen MacDonald

A filtered manifold is a smooth manifold $M$ together with a filtration of the tangent bundle by smooth subbundles which is compatible with the Lie bracket of vector fields in a certain sense. The Lie bracket of vector fields then induces a…

Differential Geometry · Mathematics 2017-09-07 Andreas Cap

First we confirm a conjecture asserting that any compact K\"ahler manifold $N$ with $\Ric^\perp>0$ must be simply-connected by applying a new viscosity consideration to Whitney's comass of $(p, 0)$-forms. Secondly we prove the projectivity…

Differential Geometry · Mathematics 2020-09-23 Lei Ni

For Fano-Mori fibre spaces $\pi\colon V\to S$, every fibre of which is a primitive Fano variety with the global canonical threshold at least 1, and which are stable with respect to birational modifications of the base and sufficiently…

Algebraic Geometry · Mathematics 2023-11-21 Aleksandr V. Pukhlikov

Let $\varphi_t : M \to M$ be a flow on a smooth closed connected manifold $M$ that preserves and expands a foliation $F$. We establish a theorem of propagation of regularity along the leaves of $F$ for sections of vector bundles satisfying…

Dynamical Systems · Mathematics 2026-02-17 Thibault Lefeuvre , Rafael Potrie

We investigate the structure of smooth holomorphic foliations with numerically flat tangent bundles on compact K\"ahler manifolds. Extending earlier results on non-uniruled projective manifolds by the second and fourth authors, we show that…

Algebraic Geometry · Mathematics 2024-11-14 Stéphane Druel , Jorge Vitório Pereira , Brent Pym , Frédéric Touzet

We study smooth foliations of arbitrary codimension on homogeneous compact K\"ahler manifolds. We prove that smooth foliations on rational compact homogeneous manifolds are locally trivial fibrations and classify the smooth foliations with…

Algebraic Geometry · Mathematics 2015-01-20 Federico Lo Bianco , Jorge Vitorio Pereira