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We compute the nef cone of the Hilbert scheme of points on a general rational elliptic surface. As a consequence of our computation, we show that the Morrison-Kawamata cone conjecture holds for these nef cones.

Algebraic Geometry · Mathematics 2019-05-14 John Kopper

We show that nef cycle classes on smooth complete spherical varieties are effective, and the products of nef cycle classes are also nef. Let X be a smooth projective spherical variety such that its effective cycle classes of codimension k…

Algebraic Geometry · Mathematics 2013-11-27 Qifeng LI

We compute the minimal exponent of the affine cone over a complete intersection of smooth projective hypersurfaces intersecting transversely. The upper bound for the minimal exponent is proved, more generally, in the weighted homogeneous…

Algebraic Geometry · Mathematics 2025-03-12 Qianyu Chen , Bradley Dirks , Mircea Mustaţă

In this article, we use the cone of nef curves to study minimal log discrepancies. The first result is an improvement of the nef cone theorem in the case of log Calabi-Yau dlt pairs. Then, we prove that the ascending chain condition for…

Algebraic Geometry · Mathematics 2021-09-21 Joaquín Moraga

Following ideas of V. Batyrev, we prove an analogue of the Cone Theorem for the closed cone of nef curves: an enlargement of the cone of nef curves is the closure of the sum of a K_X-non-negative portion and countably many K_X-negative…

Algebraic Geometry · Mathematics 2011-03-03 Brian Lehmann

Nef and effective cones of divisors have been the subject of much study. In contrast, their higher codimension analogues are much harder to compute and few examples exist in the literature. In this paper we compute the nef cones in…

Algebraic Geometry · Mathematics 2024-03-15 Gwyneth Moreland

We illustrate the typical usage of Bayer and Macr\`{i}'s Positivity Lemma to compute the nef cones of the Hilbert schemes $X^{[n]}$ by combining the Bridgeland stability methods (for large $n$) and classical methods (for small $n$). We use…

Algebraic Geometry · Mathematics 2025-12-22 Uttaran Dutta , Sean Edwards , Neelarnab Raha

Let ${\bf C}$ be a smooth geometrically connected projective curve over a finite field, and let $A$ be the affine algebra of its regular functions outside a fixed place of ${\bf C}$. We give precise relationships between the Mahler…

Algebraic Geometry · Mathematics 2025-11-03 Jean-Benoît Bost , Frédéric Paulin

We prove that for smooth projective threefolds whose anticanonical divisors are nef, the second Chern classes are pseudo-effective under a weak assumption. As an application, the pseudo-effectivity of the second Chern classes implies that…

Algebraic Geometry · Mathematics 2007-05-23 Qihong Xie

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

Let $X = \mathbb{P}(E_1) \times_C \mathbb{P}(E_2)$ where $C$ is a smooth curve and $E_1$, $E_2$ are vector bundles over $C$.In this paper we compute the pseudo effective cones of higher codimension cycles on $X$.

Algebraic Geometry · Mathematics 2020-01-14 Rupam Karmakar

Let (X,H) be a polarized, smooth, complex projective surface, and let v be a Chern character on X with positive rank and sufficiently large discriminant. In this paper, we compute the Gieseker wall for v in a slice of the stability manifold…

Algebraic Geometry · Mathematics 2016-03-11 Izzet Coskun , Jack Huizenga

In this paper, which is a sequel of [BKLV], we study the convex-geometric properties of the cone of pseudoeffective $n$-cycles in the symmetric product $C_d$ of a smooth curve $C$. We introduce and study the Abel-Jacobi faces, related to…

Algebraic Geometry · Mathematics 2023-01-18 Francesco Bastianelli , Alexis Kouvidakis , Angelo Felice Lopez , Filippo Viviani

We classify minimal-degree curves in the Hilbert schemes of points on algebraic surfaces. When the algebraic surface is the projective plane, the nef cone and a flip structure of these Hilbert schemes are determined.

Algebraic Geometry · Mathematics 2007-05-23 Wei-ping Li , Zhenbo Qin , Qi Zhang

We introduce a new vector space associated to projective variety, the Weil Neron-Severi space, which we show is finitely generated and contains the usual Neron-Severi space as a subspace. We define the Nef cone of Weil divisor and the cone…

Algebraic Geometry · Mathematics 2014-11-17 Alberto Chiecchio

In this paper we show that a smooth toric variety $X$ of Picard number $r\leq 3$ always admits a nef primitive collection supported on a hyperplane admitting non-trivial intersection with the cone $\Nef(X)$ of numerically effective divisors…

Algebraic Geometry · Mathematics 2022-05-24 Michele Rossi , Lea Terracini

Let $f:X \to \mathbb{P}^1$ be a non-isotrivial family of semi-stable curves of genus $g\geq 1$ defined over an algebraically closed field $k$ with $s_{nc}$ singular fibers whose Jacobians are non-compact. We prove that $s_{nc}\geq 5$ if…

Algebraic Geometry · Mathematics 2016-04-06 Xin Lu , Sheng-Li Tan , Wan-Yuan Xu , Kang Zuo

We present an algorithm for solving the discrete logarithm problem in Jacobians of families of plane curves whose degrees in $X$ and $Y$ are low with respect to their genera. The finite base fields $\FF_q$ are arbitrary, but their sizes…

Cryptography and Security · Computer Science 2009-12-20 Andreas Enge , Pierrick Gaudry , Emmanuel Thomé

We construct harmonic diffeomorphisms from the complex plane $C$ onto any Hadamard surface $M$ whose curvature is bounded above by a negative constant. For that, we prove a Jenkins-Serrin type theorem for minimal graphs in $M\times R$ over…

Differential Geometry · Mathematics 2008-07-08 Jose A. Galvez , Harold Rosenberg

Let $\pi: X \to Y$ be a morphism of projective varieties and suppose that $\alpha$ is a pseudo-effective numerical cycle class satisfying $\pi_*\alpha = 0$. A conjecture of Debarre, Jiang, and Voisin predicts that $\alpha$ is a limit of…

Algebraic Geometry · Mathematics 2017-05-17 Mihai Fulger , Brian Lehmann