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We show that for any ample line bundle on a smooth complex projective variety with nonnegative Kodaira dimension, the semistability of co-Higgs bundles of implies the semistability of bundles. Then we investigate the criterion for surface…

Algebraic Geometry · Mathematics 2016-06-07 Edoardo Ballico , Sukmoon Huh

K3 surfaces have been studied from many points of view, but the positivity of the cotangent bundle is not well understood. In this paper we explore the surprisingly rich geometry of the projectivised cotangent bundle of a very general…

Algebraic Geometry · Mathematics 2026-05-27 Fabrizio Anella , Andreas Höring

In this note, we discuss the concept of pseudoeffective vector bundle and also introduce pseudoeffective torsion-free sheaves over compact K\"ahler manifolds. We show that a pseudoeffective reflexive sheaf over a compact K\"ahler manifold…

Algebraic Geometry · Mathematics 2022-04-29 Xiaojun Wu

Let $X$ be a Hyperk\"ahler manifold, and let $H$ be an ample divisor on $X$. We give a lower bound in terms of the Beauville-Bogomolov form $q(H)$ for the twisted cotangent bundle $\Omega_X \otimes H$ to be pseudoeffective. If $X$ is…

Algebraic Geometry · Mathematics 2019-06-28 Fabrizio Anella , Andreas Höring

Let $E$ be the Whitney sum of complex line bundles over a topological space $X$. Then, the projectivization $P(E)$ of $E$ is called a \emph{projective bundle} over $X$. If $X$ is a non-singular complete toric variety, so is $P(E)$. In this…

Algebraic Topology · Mathematics 2017-01-10 Suyoung Choi , Seonjeong Park

Let $M$ be a compact, holomorphic symplectic Kaehler manifold, and $L$ a non-trivial line bundle admitting a metric of semi-positive curvature. We show that some power of $L$ is effective. This result is related to the hyperkaehler SYZ…

Algebraic Geometry · Mathematics 2010-04-07 Misha Verbitsky

Classification theory and the study of projective varieties which are covered by rational curves of minimal degrees naturally leads to the study of families of singular rational curves. Since families of arbitrarily singular curves are hard…

Algebraic Geometry · Mathematics 2007-05-23 Stefan Kebekus

This is a survey article on recent results on vector bundles on symmetric product of non-singular projective curves.

Algebraic Geometry · Mathematics 2017-02-20 D. S. Nagaraj

We give an overview of partial positivity conditions for line bundles, mostly from a cohomological point of view. Although the current work is to a large extent of expository nature, we present some minor improvements over the existing…

Algebraic Geometry · Mathematics 2015-04-17 Daniel Greb , Alex Küronya

A tangent category is a categorical abstraction of the tangent bundle construction for smooth manifolds. In that context, Cockett and Cruttwell develop the notion of differential bundle which, by work of MacAdam, generalizes the notion of…

Category Theory · Mathematics 2024-09-02 Michael Ching

In this paper, we prove that a compact K\"ahler manifold $X$ with pseudo-effective (resp. singular positively curved) tangent bundle admits a smooth (resp. locally constant) rationally connected fibration $\phi \colon X \to Y$ onto a finite…

Algebraic Geometry · Mathematics 2025-02-04 Shin-ichi Matsumura , Chenghao Qing

We prove some general results on syzygies of smooth projective varieties with numerically trivial canonical line bundle. This allows to confirm several cases of Mukai's syzygies conjecture for finite quotients of abelian varieties in any…

Algebraic Geometry · Mathematics 2025-09-22 Federico Caucci

In this paper, we study when positivity conditions of vector bundles are preserved by extension. We prove that an extension of a big (resp. pseudo-effective) line bundle by an ample (resp. a nef) vector bundle is big (resp.…

Algebraic Geometry · Mathematics 2023-12-18 Sho Ejiri , Osamu Fujino , Masataka Iwai

We begin by formally defining n-Tango curves and n-Raynaud surfaces. Our investigation then focuses on the pathological behaviors exhibited by n-Raynaud surfaces. As a direct corollary of this analysis, we present a concise disproof of…

Algebraic Geometry · Mathematics 2025-07-28 Yongming Zhang

A diffeological connection on a diffeological vector pseudo-bundle is defined just the usual one on a smooth vector bundle; this is possible to do, because there is a standard diffeological counterpart of the cotangent bundle. On the other…

Differential Geometry · Mathematics 2017-01-19 Ekaterina Pervova

We present here some conjectures on the diagonalizability of uniform principal bundles on rational homogeneous spaces, that are natural extensions of classical theorems on uniform vector bundles on the projective space, and study the…

Algebraic Geometry · Mathematics 2025-04-01 Roberto Muñoz , Gianluca Occhetta , Luis E. Solá Conde

We study smooth projective complex varieties with ample cotangent bundle. Our main result is that in an abelian variety of dimension n, a complete intersection of at least n/2 general hypersurfaces of sufficiently high degrees has ample…

Algebraic Geometry · Mathematics 2011-09-08 O. Debarre

We study the complex-analytic geometry of semi-positive holomorphic line bundles on compact K\"ahler manifolds. In one of our main results, for a $\mathbb{Q}$-effective line bundle satisfying a natural torsion-type assumption, we show the…

Complex Variables · Mathematics 2026-01-23 Takayuki Koike

The quantum hyperplane section theorem is explained for nonnegative decomposable concavex bundle spaces over generalized flag manifolds.

Algebraic Geometry · Mathematics 2007-05-23 Bumsig Kim

We prove that a projective contact manifold X with second Betti number at least 2 whose canonical bundle K_X is not nef, is always the projectivised tangent bundle P(T_Y) of a projective manifold Y. It is expected that the canonical bundle…

Algebraic Geometry · Mathematics 2007-05-23 Stefan Kebekus , Thomas Peternell , Andrew J. Sommese , Jaroslaw Wisniewski