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We establish the elliptic blowup equations for E-strings and M-strings and solve elliptic genera and refined BPS invariants from them. Such elliptic blowup equations can be derived from a path integral interpretation. We provide toric…

High Energy Physics - Theory · Physics 2020-08-26 Jie Gu , Babak Haghighat , Albrecht Klemm , Kaiwen Sun , Xin Wang

We study the Seshadri constants of cyclic coverings of smooth surfaces. The existence of an automorphism on these surfaces can be used to produce Seshadri exceptional curves. We give a bound for multiple Seshadri constants on cyclic…

Algebraic Geometry · Mathematics 2007-05-23 Luis Fuentes Garcia

A striking result of McDuff and Schlenk asserts that in determining when a four-dimensional symplectic ellipsoid can be symplectically embedded into a four-dimensional symplectic ball, the answer is governed by an "infinite staircase"…

Symplectic Geometry · Mathematics 2022-11-02 Dan Cristofaro-Gardiner

We consider the embedding function $c_b(a)$ describing the problem of symplectically embedding an ellipsoid $E(1,a)$ into the smallest possible scaling by $\lambda>1$ of the polydisc $P(1,b)$. In particular, we calculate rigid-flexible…

Symplectic Geometry · Mathematics 2025-08-11 Andrew Lee , Cory H. Colbert

The ellipsoid embedding function of a symplectic four-manifold measures the amount by which its symplectic form must be scaled in order for it to admit an embedding of an ellipsoid of varying eccentricity. This function generalizes the…

Symplectic Geometry · Mathematics 2025-01-29 Caden Farley , Tara Holm , Nicki Magill , Jemma Schroder , Morgan Weiler , Zichen Wang , Elizaveta Zabelina

Working over C, we show that, apart possibly from a unique limit point, the possible values of multi-point Seshadri constant for general points on smooth projective surfaces form a discrete set. In addition to its theoretical interest, this…

Algebraic Geometry · Mathematics 2007-09-26 Brian Harbourne , Joaquim Roe

A broadly applicable geometric approach for constructing nef divisors on blow ups of algebraic surfaces at n general points is given; it works for all surfaces in all characteristics for any n. This construction is used to obtain…

Algebraic Geometry · Mathematics 2007-05-23 Brian Harbourne

We prove that an $n$-dimensional complex projective variety is isomorphic to $\mathbb{P}^n$ if the Seshadri constant of the anti-canonical divisor at some smooth point is greater than $n$. We also classify complex projective varieties with…

Algebraic Geometry · Mathematics 2018-10-17 Yuchen Liu , Ziquan Zhuang

Let $X$ be a complex projective variety, and let $E_{\ast}$ be a parabolic vector bundle on $X$. We introduce the notion of \textit{parabolic Seshadri constants} of $E_{\ast}$. It is shown that these constants are analogous to the classical…

Algebraic Geometry · Mathematics 2023-06-08 Indranil Biswas , Krishna Hanumanthu , Snehajit Misra , Nabanita Ray

The third named author has been developing a theory of "higher" symplectic capacities. These capacities are invariant under taking products, and so are well-suited for studying the stabilized embedding problem. The aim of this note is to…

Symplectic Geometry · Mathematics 2022-02-21 Dan Cristofaro-Gardiner , Richard Hind , Kyler Siegel

We construct symplectic embeddings of ellipsoids of dimension $2n \ge 6$ into the product of a 4-ball or 4-dimensional cube with Euclidean space. A sequence of these embeddings can be shown to be optimal.

Symplectic Geometry · Mathematics 2017-05-17 Richard Hind

In this article we compute Seshadri constants of ample line bundles on the blowup of Hirzebruch surface $\mathbb{F}_e$ at $r\leqslant e+3$ very general points. Similarly, we compute Seshadri constants on the blowups of certain decomposable…

Algebraic Geometry · Mathematics 2025-01-10 Cyril J. Jacob , Bivas Khan , Ronnie Sebastian

Quite recently, McDuff showed that the existence of a symplectic embedding of one four-dimensional ellipsoid into another can be established by comparing their corresponding sequences of ECH capacities. In this note we show that these…

Symplectic Geometry · Mathematics 2011-03-01 David Bauer

This note constructs sharp obstructions for stabilized symplectic embeddings of an ellipsoid into a ball, in the case when the initial four-dimensional ellipsoid has `eccentricity' of the form 3n-1 for some integer n.

Symplectic Geometry · Mathematics 2018-11-28 Dusa McDuff

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

We study Seshadri constants of ample line bundles on hyperelliptic surfaces. We obtain new lower bounds and compute the exact values of Seshadri constants in some cases. Our approach uses results of F. Serrano (1990), B. Harboune and J. Roe…

Algebraic Geometry · Mathematics 2015-02-13 Lucja Farnik

One of Demailly's characterizations of Seshadri constants on ample line bundles works with Lelong numbers of certain positive singular hermitian metrics. In this note sections of multiples of the line bundle are used to produce such metrics…

Algebraic Geometry · Mathematics 2007-05-23 Thomas Eckl

We apply the theory of Seshadri stratifications to embedded toric varieties $X_P\subseteq \mathbb P(V)$ associated with a normal lattice polytope $P$. The approach presented here is purely combinatorial and completely independent of…

Algebraic Geometry · Mathematics 2025-05-06 Rocco Chirivì , Martina Costa Cesari , Xin Fang , Peter Littelmann

This note describes a correct way to perform the inflation procedures claimed in the papers on embedding ellipsoids, Journ. Top. 2 (2009), 1-22 and 589-623. The idea is to inflate along a collection of transversally and positively…

Symplectic Geometry · Mathematics 2017-05-17 Dusa McDuff

The ellipsoidal capacity function of a symplectic four manifold $X$ measures how much the form on $X$ must be dilated in order for it to admit an embedded ellipsoid of eccentricity $z$. In most cases there are just finitely many…

Symplectic Geometry · Mathematics 2023-08-01 Nicki Magill , Dusa McDuff , Morgan Weiler