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Working over the complex field and formalizing and sharpening approaches introduced by several authors, we give a method for verifying when a divisor on a blow up of P^2 at general points is nef. The method is useful both theoretically and…

Algebraic Geometry · Mathematics 2007-09-26 B. Harbourne , J. Roe

We establish an improvement of Philippon's zero estimates primarily in the multiplicity setting. The improvement is made possible by a more geometric approach and in particular the use of Seshadri constants.

Number Theory · Mathematics 2007-10-15 Michael Nakamaye , Nicolas Ratazzi

In the paper we present an alternative approach to the boundedness of Seshadri constants (which measure the local positivity) of nef and big line bundles at a general point of a complex--projective variety. Our approach is based on the…

alg-geom · Mathematics 2008-02-03 Oliver Küchle , Andreas Steffens

We refine results of Hwang, Keum and Szemberg, Tutaj-Gasinska which relate local invariants - Seshadri constants - of ample line bundles on surfaces to the global geometry - fibration structure. We show that the same picture emerges when…

Algebraic Geometry · Mathematics 2007-09-18 Wioletta Syzdek , Tomasz Szemberg

Motivated by asymptotic phenomena of moduli spaces of higher rank stable sheaves on algebraic surfaces, we study the Picard number of the moduli space of one-dimensional stable sheaves supported in a sufficiently positive divisor class on a…

Algebraic Geometry · Mathematics 2025-03-11 Fei Si , Feinuo Zhang

The purpose of this paper is to study Seshadri constants on the self-product $E\times E$ of an elliptic curve $E$. We provide explicit formulas for computing the Seshadri constants of all ample line bundles on the surfaces considered. As an…

Algebraic Geometry · Mathematics 2008-06-30 Thomas Bauer , Christoph Schulz

In the present note, we focus on certain properties of special curves that might be used in the theory of multi-point Seshadri constants for ample line bundles on the complex projective plane. In particular, we provide three…

Algebraic Geometry · Mathematics 2023-01-10 Piotr Pokora

We compute in this note the Seshadri constants of the anticanonical bundle at every point of Del Pezzo surfaces. During the proof, we enlight the role of rational curves in our computations. We present then two exemples where the positivity…

Algebraic Geometry · Mathematics 2007-05-23 Amaël Broustet

We prove a sharp lower bound on the curvatures of non-flat ASD connections over the cylinder.

Differential Geometry · Mathematics 2012-04-06 Masaki Tsukamoto

We compute Seshadri constants of a torus equivariant nef vector bundle on a projective space satisfying certain conditions. As an application, we compute Seshadri constants of tangent bundles on projective spaces. We also consider…

Algebraic Geometry · Mathematics 2021-05-11 Jyoti Dasgupta , Bivas Khan , Aditya Subramaniam

In this paper we will propose a new method to investigate Seshadri constants, namely by means of (nested) Hilbert schemes. This will allow us to use the geometry of the latter spaces, for example the computations of the nef cone via…

Algebraic Geometry · Mathematics 2024-09-17 Jonas Baltes

Consider a polarized abelian variety $(A,L)$ over the field of complex numbers. Following Demailly, one can associate to $(A,L)$ a real number $\epsilon(A,L)$, its {\em Seshadri constant}, which in effect measures how much of the positivity…

Algebraic Geometry · Mathematics 2007-05-23 Thomas Bauer

We give a bound on the H-constants of configurations of smooth curves having transversal intersection points only on an algebraic surface of non-negative Kodaira dimension. We also study in detail configurations of lines on smooth complete…

Algebraic Geometry · Mathematics 2019-12-05 Roberto Laface , Piotr Pokora

Let $e,r \ge 0$ be integers and let $\mathbb{F}_e : = \mathbb{P}(\mathcal{O}_{\mathbb{P}^1} \oplus \mathcal{O}_{\mathbb{P}^1}(-e))$ denote the Hirzebruch surface with invariant $e$. We compute the Seshadri constants of an ample line bundle…

Algebraic Geometry · Mathematics 2024-10-28 Krishna Hanumanthu , Cyril J. Jacob , Suhas B. N. , Amit Kumar Singh

For three dimensional complete Riemannian manifolds with scalar curvature no less than one, we obtain the sharp upper bound of complete stable minimal surfaces' diameter.

Differential Geometry · Mathematics 2025-05-27 Qixuan Hu , Guoyi Xu , Shuai Zhang

The Lipschitz constant of a response surface function upper bounds the sensitivity of a dependent variable to changes in the independent ones. Traditionally, such constants have found much implicit and abstract use in mathematically…

Optimization and Control · Mathematics 2017-01-17 Gene A. Bunin , Grégory François

In this paper we compute the $r$-point Seshadri constant on $\mathbb{P}^1\times\mathbb{P}^1$ for those line bundles where the answer might be expected to be governed by $(-1)$-curves. As a consequence we obtain explicit formulas for the…

Algebraic Geometry · Mathematics 2025-11-25 Chris Dionne , Mike Roth

Extending work of M. Zarzar, we evaluate the potential of Goppa-type evaluation codes constructed from linear systems on projective algebraic surfaces with small Picard number. Putting this condition on the Picard number provides some…

Information Theory · Computer Science 2018-03-02 John Little , Hal Schenck

Given a nef and big line bundle $L$ on a projective variety $X$ of dimension $d \geq 2$, we prove that the Seshadri constant of $L$ at a very general point is larger than $(d+1)^{\frac{1}{d}-1}$. This slightly improves the lower bound $1/d$…

Algebraic Geometry · Mathematics 2022-03-15 François Ballaÿ

We define the Seshadri constant of a space curve and consider ways to estimate it. We then show that it governs the gonality of the curve. We use an argument based on Bogomolov's instability theorem on a threefold. The same methods are then…

alg-geom · Mathematics 2008-02-03 Roberto Paoletti