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Related papers: Remark on nefness in higher codimension

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We study generalizations for higher codimension cycles of several well-known definitions of the nef cone of divisors on a projective variety. These generalizations fix some of the pathologies exhibited by the classical nef cone of higher…

Algebraic Geometry · Mathematics 2016-01-14 Mihai Fulger , Brian Lehmann

We reduce the Abundance Conjecture in dimension 4 to the following numerical statement: if the canonical divisor K is nef and has maximal nef dimension, then K is big. From this point of view, we ``classify'' in dimension 2 nef divisors…

Algebraic Geometry · Mathematics 2007-05-23 Florin Ambro

Using currents with minimal singularities, we construct pointwise minimal multiplicities for a real pseudo-effective $(1,1)$-class $\alpha$ on a compact complex $n$-fold $X$, which are the local obstructions to the numerical effectivity of…

Algebraic Geometry · Mathematics 2016-09-07 Sebastien Boucksom

The goal of this work is to study positivity of subvarieties with nef normal bundle in the sense of intersection theory. After Ottem's work on ample subschemes, we introduce the notion of a nef subscheme, which generalizes the notion of a…

Algebraic Geometry · Mathematics 2019-07-10 Chung-Ching Lau

We solve Teissier's proportionality problem for transcendental nef classes over a compact K\"ahler manifold which says that the equality in the Khovanskii-Teissier inequalities hold for two nef and big classes if and only if the two classes…

Algebraic Geometry · Mathematics 2014-10-21 Jixiang Fu , Jian Xiao

Boucksom, Favre and Jonsson establish in [4] an analog of Diskant's inequality in convex geometry for nef and big line bundles on a complete algebraic variety over an algebraically closed field of characteristic zero (Theorem F [4]), from…

Algebraic Geometry · Mathematics 2013-04-05 Steven Dale Cutkosky

The nef cone of a projective variety Y is an important and often elusive invariant. In this paper we construct two polyhedral lower bounds and one polyhedral upper bound for the nef cone of Y using an embedding of Y into a toric variety.…

Algebraic Geometry · Mathematics 2011-06-14 Angela Gibney , Diane Maclagan

This work discusses combinatorial and arithmetic aspects of cohomology vanishing for divisorial sheaves on toric varieties. We obtain a refined variant of the Kawamata-Viehweg theorem which is slightly stronger. Moreover, we prove a new…

Algebraic Geometry · Mathematics 2012-01-30 Markus Perling

We prove a Kawamata-Viehweg vanishing theorem on a normal compact Kahler space X: if L is a nef line bundle with numerical dimension at least equal to 2, then the q-th cohomology group of K_X+L vanishes for q at least equal to the dimension…

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

We introduce a notion of volume of a normal isolated singularity that generalizes Wahl's characteristic number of surface singularities to arbitrary dimensions. We prove a basic monotonicity property of this volume under finite morphisms.…

Algebraic Geometry · Mathematics 2019-12-19 Sebastien Boucksom , Tommaso De Fernex , Charles Favre

In an earlier work, we investigated some consequences of the existence of a K\"ahler metric of negative holomorphic sectional curvature on a projective manifold. In the present work, we extend our results to the case of semi-negative (i.e.,…

Algebraic Geometry · Mathematics 2015-06-10 Gordon Heier , Steven S. Y. Lu , Bun Wong

We prove a decomposition theorem for the nef cone of smooth fiber products over curves, subject to the necessary condition that their N\'eron--Severi space decomposes. We apply it to describe the nef cone of so-called Schoen varieties,…

Algebraic Geometry · Mathematics 2024-03-04 Cécile Gachet , Hsueh-Yung Lin , Long Wang

A nef-partition for a weighted complete intersection is a combinatorial structure on its weights and degrees which is important for Mirror Symmetry. It is known that nef-partitions exist for smooth well-formed Fano weighted complete…

Algebraic Geometry · Mathematics 2023-12-13 Mikhail Ovcharenko

We describe MBM classes for irreducible holomorphic symplectic manifolds of K3 and Kummer types. These classes are the monodromy images of extremal rational curves which give the faces of the nef cone of some birational model. We study the…

Algebraic Geometry · Mathematics 2025-04-21 Anastasia V. Vikulova

We give a relation between the existence of a Zariski decomposition and the behavior of the restricted volume of a big divisor on a smooth (complex) projective variety. Moreover, we give an analytic description of the restricted volume in…

Algebraic Geometry · Mathematics 2013-01-17 Shin-ichi Matsumura

In this article we construct many examples of properly convex irreducible domains divided by Zariski dense relatively hyperbolic groups in every dimension at least 3. This answers a question of Benoist. Relative hyperbolicity and non-strict…

Geometric Topology · Mathematics 2025-07-16 Pierre-Louis Blayac , Gabriele Viaggi

On a projective surface it is well-known that the set of curves orthogonal to a nef line bundle is either finite or uncountable. We show that this dichotomy fails in higher dimension by constructing a nef line bundle on a threefold which is…

Algebraic Geometry · Mathematics 2014-10-17 John Lesieutre , John Christian Ottem

Generalising a classical theorem by Ueno, we prove structure results for manifolds with nef or semiample cotangent bundle.

Algebraic Geometry · Mathematics 2017-11-07 Andreas Höring

We give degree lower bounds for quotient line bundles of the lowest piece of a Hodge module induced by a complex variation of Hodge structures outside a simple normal crossing divisor, beyond the unipotent variation case. This note aims to…

Algebraic Geometry · Mathematics 2026-05-14 Ze Yun

We employ the formalism of vanishing cycles and perverse sheaves to introduce and study the vanishing cohomology of complex projective hypersurfaces. As a consequence, we give upper bounds for the Betti numbers of projective hypersurfaces,…

Algebraic Geometry · Mathematics 2022-09-15 Laurenţiu Maxim , Laurenţiu Păunescu , Mihai Tibăr
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