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We prove a symmetric version of B\'ezout's theorem. More precisely, we show that the symmetric orbit type of a transverse intersection of complex symmetric hypersurfaces in projective space is determined by the degrees. In the projective…

Algebraic Geometry · Mathematics 2024-10-01 Samuel Lidz , Zachary Lihn , Adam Melrod

Given two general rational curves of the same degree in two projective spaces, one can ask whether there exists a third rational curve of the same degree that projects to both of them. We show that, under suitable assumptions on the degree…

Algebraic Geometry · Mathematics 2022-05-24 Matteo Gallet , Josef Schicho

Bezout's theorem gives us the degree of intersection of two properly intersecting projective varieties. As two curves in P^3 never intersect properly, Bezout's theorem cannot be directly used to bound the number of intersection points of…

Algebraic Geometry · Mathematics 2014-03-13 R. Hartshorne , R. M. Miró-Roig

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 address the problem of computing bounds for the self-intersection number (the minimum number of self-intersection points) of members of a free homotopy class of curves in the doubly-punctured plane as a function of their combinatorial…

Geometric Topology · Mathematics 2010-01-27 Moira Chas , Anthony Phillips

In this paper, we consider rational cuspidal plane curves having at least three cusps. We give an upper bound of the self-intersection number of the proper transforms of such curves via the minimal embedded resolution of the cusps. For a…

Algebraic Geometry · Mathematics 2014-08-04 Keita Tono

For each integer $k \in [0,9]$, we count the number of plane cubic curves defined over a finite field $\mathbb{F}_q$ that do not share a common component and intersect in exactly $k\ \mathbb{F}_q$-rational points. We set this up as a…

Number Theory · Mathematics 2022-01-24 Nathan Kaplan , Vlad Matei

We establish new bounds on the number of tangencies and orthogonal intersections determined by an arrangement of curves. First, given a set of $n$ algebraic plane curves, we show that there are $O(n^{3/2})$ points where two or more curves…

Combinatorics · Mathematics 2018-07-10 Jordan S. Ellenberg , Jozsef Solymosi , Joshua Zahl

This paper is devoted to presenting a new approach to determine the intersection of two quadrics based on the detailed analysis of its projection in the plane (the so called cutcurve) allowing to perform the corresponding lifting correctly.…

Computational Geometry · Computer Science 2019-06-26 Alexandre Trocado , Laureano Gonzalez-Vega

We study the following question: fix a sufficient general curve D of degree d in P^2, what is the least number of intersections between D and an irreducible curve of degree m? G. Xu proved this number i(d, m) is at least d - 2 for all m.…

Algebraic Geometry · Mathematics 2007-05-23 Xi Chen

We obtain an upper bound for the volume of the convex hull of a simple closed Frenet curve with exactly four vertices, i.e., four points of vanishing torsion, and lying on the boundary of its convex hull. Moreover, we show that the upper…

Differential Geometry · Mathematics 2026-03-13 Jakob Bohr , Steen Markvorsen , Matteo Raffaelli

A classical inequality which is due to Lickorish and Hempel says that the distance between two curves in the curve complex can be measured by their intersection number. In this paper, we show a converse version; the intersection number of…

Geometric Topology · Mathematics 2016-04-27 Yohsuke Watanabe

In this note we address the problem of determining the maximum number of points of intersection of two arithmetically Cohen-Macaulay curves in $\PP^3$. We give a sharp upper bound for the maximum number of points of intersection of two…

Algebraic Geometry · Mathematics 2007-05-23 R. M. Miro-Roig , K. Ranestad

The maximum cut problem for a quintic del Pezzo surface ${\rm Bl}_{4}(\mathbb{P}^2)$ asks: Among all partitions of the 10 exceptional curves into two disjoint sets, what is the largest possible number of pairwise intersections? In this…

Combinatorics · Mathematics 2012-07-18 Mauricio Junca Mauricio Velasco

We obtain a new bound on the number of two-rich points spanned by an arrangement of low degree algebraic curves in $\mathbb{R}^4$. Specifically, we show that an arrangement of $n$ algebraic curves determines at most $C_\epsilon…

Combinatorics · Mathematics 2018-01-19 Larry Guth , Joshua Zahl

We show that there exist mathematical 4-instanton bundles F on the projective 3-space such that F(2) is globally generated (by four global sections). This is equivalent to the existence of elliptic space curves of degree 8 defined by…

Algebraic Geometry · Mathematics 2016-04-08 Cristian Anghel , Iustin Coanda , Nicolae Manolache

Let C be a smooth cubic curve in the complex projective plane. We show that for every positive integer k, there are only finite number of rational curves of degree k each intersects the cubic C at exactly one point. The number of such…

alg-geom · Mathematics 2008-02-03 Geng Xu

Classically, B\'ezout's theorem says that an intersection of hypersurfaces in a projective space is rationally equivalent to a number of copies of a smaller projective space, the number depending on the degrees of the hypersurfaces. We give…

Algebraic Topology · Mathematics 2023-12-04 Steven R. Costenoble , Thomas Hudson

We consider systems of simple closed curves on surfaces and their total number of intersection points, their so-called crossing number. For a fixed number of curves, we aim to minimise the crossing number. We determine the minimal crossing…

Geometric Topology · Mathematics 2024-03-11 Jasmin Jörg

Let $X$ be an algebraic variety, defined over the rationals. This paper gives upper bounds for the number of rational points on $X$, with height at most $B$, for the case in which $X$ is a curve or a surface. In the latter case one excludes…

Number Theory · Mathematics 2007-05-23 D. R. Heath-Brown , J. -L. Colliot-Thélène
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