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Related papers: Varieties with generically nef tangent bundles

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Using recent results of Bayer-Macr\`i, we compute in many cases the pseudoeffective and nef cones of the projectivised cotangent bundle of a smooth projective K3 surface. We then use these results to construct explicit families of smooth…

Algebraic Geometry · Mathematics 2025-09-16 Frank Gounelas , John Christian Ottem

In this paper, we prove that a non-projective compact K\"ahler three-fold with nef anti-canonical bundle is, up to a finite \'etale cover, one of the following: a manifold with vanishing first Chern class; the product of a K3 surface and…

Algebraic Geometry · Mathematics 2025-01-09 Shin-ichi Matsumura , Xiaojun Wu

Let $X$ be a smooth projective variety defined over an algebraically closed field of positive characteristic $p$ whose tangent bundle is nef. We prove that $X$ admits a smooth morphism $X \to M$ such that the fibers are Fano varieties with…

Algebraic Geometry · Mathematics 2020-12-18 Akihiro Kanemitsu , Kiwamu Watanabe

We study projective manifolds with nonamenable and non-residually finite fundamental groups. We generalize the uniformization theorem of our earlier note. We generalize a classical theorem of Maltsev about finitely generated subgroups of…

Algebraic Geometry · Mathematics 2017-10-04 Robert Treger

We prove that Fano 5-folds with nef tangent bundles are rational homogeneous manifolds.

Algebraic Geometry · Mathematics 2015-03-17 Akihiro Kanemitsu

In this paper we prove the following abundance-type result: for any smooth Fano variety $X$, the tangent bundle $T_X$ is nef if and only if it is big and semiample in the sense that the tautological line bundle…

Algebraic Geometry · Mathematics 2025-12-04 Juanyong Wang

We show that a compact Kahler manifold with nonpositive holomorphic sectional curvature has nef canonical bundle. If the holomorphic sectional curvature is negative then it follows that the canonical bundle is ample, confirming a conjecture…

Differential Geometry · Mathematics 2017-10-24 Valentino Tosatti , Xiaokui Yang

In this note, we describe the structure of regular foliations with semi-positive anti-canonical bundle on smooth projective varieties.

Algebraic Geometry · Mathematics 2018-10-17 Stéphane Druel

The paper consists of three parts. In the first of them different kinds stability are discussed. In particular, the stability concept with respect to nef divisor is introduced. A structure of rigid and superrigid vector bundles on smooth…

alg-geom · Mathematics 2008-02-03 Sergej A. Kuleshov

We study complex projective manifolds X that admit surjective endomorphisms f:X->X of degree at least two. In case f is etale, we prove structure theorems that describe X. In particular, a rather detailed description is given if X is a…

Algebraic Geometry · Mathematics 2007-06-22 Marian Aprodu , Stefan Kebekus , Thomas Peternell

We show that smooth projective horospherical varieties with nef tangent bundles are rational homogeneous spaces.

Algebraic Geometry · Mathematics 2015-12-16 Qifeng Li

We provide supplements and open problems related to structure theorems for maximal rationally connected fibrations of certain positively curved projective varieties, including smooth projective varieties with semi-positive holomorphic…

Algebraic Geometry · Mathematics 2022-11-18 Shin-ichi Matsumura

We prove that Fano n-folds with nef tangent bundle and Picard number greater than n-5 are rational homogeneous manifolds.

Algebraic Geometry · Mathematics 2015-05-13 Akihiro Kanemitsu

The goal of this work is to pursue the study of pseudo-effective line bundles and vector bundles. Our first result is a generalization of the Hard Lefschetz theorem for cohomology with values in a pseudo-effective line bundle. The Lefschetz…

Algebraic Geometry · Mathematics 2007-05-23 Jean-Pierre Demailly , Thomas Peternell , Michael Schneider

We present bounds for the geometric degree of the tangent bundle and the tangential variety of a smooth affine algebraic variety $V$ in terms of the geometric degree of $V$. We first analyze the case of curves, showing an explicit relation…

Algebraic Geometry · Mathematics 2024-03-19 Gabriela Jeronimo , Leonardo Lanciano , Pablo Solernó

We prove that smooth Fano 5-folds with nef tangent bundles and Picard numbers greater than one are rational homogeneous manifolds.

Algebraic Geometry · Mathematics 2013-04-10 Kiwamu Watanabe

Based on the recent work of K.~Zhang, we discuss the Miyaoka-Yau type inequality for projective manifolds with nef anti-canonical line bundle, assuming the lower bound of the delta-invariant introduced by Fujita and Odaka.

Differential Geometry · Mathematics 2024-07-08 Tomoyuki Hisamoto

The goal of this short note is to point out that every Fano manifold with a nef tangent bundle possesses an almost K{\"a}hler-Einstein metric, in a weak sense. The technique relies on a regularization theorem for closed positive (1,…

Complex Variables · Mathematics 2018-02-07 Jean-Pierre Demailly

In this paper, we extend the structure theorem for smooth projective varieties with nef tangent bundle to projective klt varieties whose tangent sheaf is either positively curved or almost nef. Specifically, we show that such a variety $X$,…

Algebraic Geometry · Mathematics 2025-07-23 Masataka Iwai , Shin-ichi Matsumura , Guolei Zhong

In this article we study the structure of klt projective varieties with nef anticanonical divisor (and more generally, varieties of semi-Fano type), especially the canonical fibrations associated to them. We show that: 1. the Albanese map…

Algebraic Geometry · Mathematics 2020-09-15 Juanyong Wang