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We study the intersection theory of punctured pseudoholomorphic curves in $4$-dimensional symplectic cobordisms. We first study the local intersection properties of such curves at the punctures. We then use this to develop topological…

Symplectic Geometry · Mathematics 2019-03-20 Richard Siefring

Euler-symmetric projective varieties, introduced by Baohua Fu and Jun-Muk Hwang in 2020, are nondegenerate projective varieties admitting many $\mathbb{C}^{\times}$-actions of Euler type. They are quasi-homogeneous and uniquely determined…

Algebraic Geometry · Mathematics 2023-11-30 Zhijun Luo

Let B be a finite collection of geometric (not necessarily convex) bodies in the plane. Clearly, this class of geometric objects naturally generalizes the class of disks, lines, ellipsoids, and even convex polygons. We consider geometric…

Discrete Mathematics · Computer Science 2013-08-29 Alexander Grigoriev , Athanassios Koutsonas , Dimitrios M. Thilikos

Given a hypersurface in the complex projective $n$-space we prove several known formulas for the degree of its polar map by purely algebro-geometric methods. Furthermore, we give formulas for the degree of its polar map in terms of the…

Algebraic Geometry · Mathematics 2014-02-26 Thiago Fassarella , Nivaldo Medeiros

We obtain criteria for detecting complete intersections in projective varieties. Motivated by a conjecture of Hartshorne concerning subvarieties of projective spaces, we investigate situations when two-codimensional smooth subvarieties of…

Algebraic Geometry · Mathematics 2020-12-01 Mihai Halic

In this paper we investigate the intersection problem for $1$-surfaces immersed in a complete Riemannian three-manifold $P$ with Ricci curvature bounded from below by $-2$. We first prove a Frankel's type theorem for $1$-surfaces with…

Differential Geometry · Mathematics 2022-02-10 G. Pacelli Bessa , Tiarlos Cruz , Leandro F. Pessoa

The main result is a wall crossing formula for central projections defined on submanifolds of a real projective space. Our formula gives the jump of the degree of such a projection when the center of the projection varies. The fact that the…

Algebraic Geometry · Mathematics 2014-04-04 Christian Okonek , Andrei Teleman

We show that the detection of geometric intersection in an arbitrary representation of the mapping class group of surface implies the injectivity of that representation up to center, and vice versa. As an application, we discuss the…

Geometric Topology · Mathematics 2016-12-13 Yasushi Kasahara

We address the problem of the maximal finite number of real points of a real algebraic curve (of a given degree and, sometimes, genus) in the projective plane. We improve the known upper and lower bounds and construct close to optimal…

Algebraic Geometry · Mathematics 2019-09-13 Erwan Brugallé , Alex Degtyarev , Ilia Itenberg , Frédéric Mangolte

We show that the complement of a degree $d$ hypersurface in a projective complete intersection, whose defining equations have degrees strictly larger than $d$, has a rational connectivity higher than expected. The key new feature is that a…

Algebraic Geometry · Mathematics 2010-02-05 Alexandru Dimca

For an even set of points in the plane, choose a max-sum matching, that is, a perfect matching maximizing the sum of Euclidean distances of its edges. For each edge of the max-sum matching, consider the ellipse with foci at the edge's…

Computational Geometry · Computer Science 2023-11-23 Polina Barabanshchikova , Alexandr Polyanskii

In this paper, we compute the number of self-intersections of a plane projection of a generic complete intersection curve defined by polynomials with the given support. Moreover, we discuss the tropical counterpart of this problem.

Algebraic Geometry · Mathematics 2020-03-24 Arina Voorhaar

The mapping class group of a surface $\S$ acts on the set of closed geodesics on $\S$. This action preserves self-intersection number. In this paper, we count the orbits of curves with at most $K$ self-intersections, for each $K \geq 1$.…

Geometric Topology · Mathematics 2016-07-20 Jenya Sapir

A tropical complete intersection curve C in R^(n+1) is a transversal intersection of n smooth tropical hypersurfaces. We give a formula for the number of vertices of C given by the degrees of the tropical hypersurfaces. We also compute the…

Algebraic Geometry · Mathematics 2007-11-14 Magnus Dehli Vigeland

This paper is motivated by the real symplectic isotopy problem : does there exists a nonsingular real pseudoholomorphic curve not isotopic in the projective plane to any real algebraic curve of the same degree? Here, we focus our study on…

Geometric Topology · Mathematics 2007-05-23 Erwan Brugalle

Under conditions that prevent tangential intersection, we prove quadratic convergence of a projection algorithm for the feasibility problem of finding a point in the intersection of a smooth curve and line in $\mathbb{R}^2$. This nonconvex…

Optimization and Control · Mathematics 2025-10-22 Jordan Collard , Scott B. Lindstrom

In this paper, we prove an intersection-theoretic result pertaining to curves in certain Hilbert modular surfaces in positive characteristic. Specifically, we show that given two appropriate curves C,D parameterizing abelian surfaces with…

Algebraic Geometry · Mathematics 2025-03-07 Asvin G. , Qiao He , Ananth N. Shankar

We propose a general framework governing the intersection properties of extremal rays of irreducible holomorphic symplectic manifolds under the Beauville-Bogomolov form. Our main thesis is that extremal rays associated to Lagrangian…

Algebraic Geometry · Mathematics 2010-06-08 Brendan Hassett , Yuri Tschinkel

It is well-known that theta characteristics on smooth plane curves over a field of characteristic different from two are in bijection with certain smooth complete intersections of three quadrics. We generalize this bijection to possibly…

Algebraic Geometry · Mathematics 2015-01-22 Yasuhiro Ishitsuka

We give necessary and sufficient topological conditions for a simple closed curve on a real rational surface to be approximable by smooth rational curves. We also study approximation by smooth rational curves with given complex…

Algebraic Geometry · Mathematics 2025-05-26 János Kollár , Frédéric Mangolte