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In this paper, we consider the following question: how many degree $d$ curves are there in $\mathbb{P}^3$ (passing through the right number of generic lines and points), whose image lies inside a $\mathbb{P}^2$, having $\delta$ nodes and…

Algebraic Geometry · Mathematics 2025-02-21 Nilkantha Das , Ritwik Mukherjee

We construct invariants for any closed semipositive symplectic manifold which count rational curves satisfying tangency constraints to a local divisor. More generally, we introduce invariants involving multibranched local tangency…

Symplectic Geometry · Mathematics 2021-10-20 Dusa McDuff , Kyler Siegel

We study the "generic" degenerations of curves with two singular points when the points merge. First, the notion of generic degeneration is defined precisely. Then a method to classify the possible results of generic degenerations is…

Algebraic Geometry · Mathematics 2009-04-21 Dmitry Kerner

We present an algorithm for computing curves and families of curves of prescribed degree and geometric genus on real rational surfaces.

Algebraic Geometry · Mathematics 2018-05-11 Niels Lubbes

The traditional study of plane and space algebraic curves by looking at their tangent vectors, curvatures and torsions provides geometric, but unfortunately not sufficient information about individual curves in order to be able to…

Algebraic Geometry · Mathematics 2021-03-04 Hana Melanova

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 enumerate rational curves in toric surfaces passing through points and satisfying cross-ratio constraints using tropical and combinatorial methods. Our starting point is arXiv:1509.07453, where a tropical-algebraic correspondence theorem…

Algebraic Geometry · Mathematics 2018-05-02 Christoph Goldner

Let X be a projective variety which is covered by rational curves, for instance a Fano manifold over the complex numbers. In this setup, characterization and classification problems lead to the natural question: "Given two points on X, how…

Algebraic Geometry · Mathematics 2016-11-25 Stefan Kebekus , Sandor J. Kovacs

A planar Tangle is a smooth simple closed curve piecewise defined by quadrants of circles with constant curvature. We can enumerate Tangles by counting their dual graphs, which consist of a certain family of polysticks. The number of…

Combinatorics · Mathematics 2021-03-09 Douglas A. Torrance

In this paper, we study the deformation theory of degenerate algebraic curves on singular varieties which appear as the degenerate limit of families of varieties. For this purpose, we systematically develop a new method to calculate the…

Algebraic Geometry · Mathematics 2017-05-03 Takeo Nishinou

We completely classify all plane curves of degree at most 30 with a unique cuspidal (locally unibranch) singular point and rational normalization in terms of the Newton pairs parameterizing the cusp. We distinguish between prime and…

Algebraic Geometry · Mathematics 2023-11-28 Kristin DeVleming , Nikita Singh

In this paper we obtain an explicit formula for the number of curves in a compact complex surface $X$ (passing through the right number of generic points), that has up to one node and one singularity of codimension $k$, provided the total…

Algebraic Geometry · Mathematics 2015-01-08 Somnath Basu , Ritwik Mukherjee

The purpose of this note is to provide some applications of Faltings' recent proof of S. Lang's conjecture to smooth plane curves. Let $C$ be a smooth plane curve defined by an equation of degree $d$ with integral coefficients. We show that…

alg-geom · Mathematics 2008-02-03 Olivier Debarre , Matthew Klassen

We generalize the recent work of S. Fomin and G. Mikhalkin on polynomial formulas for Severi degrees. The degree of the Severi variety of plane curves of degree d and delta nodes is given by a polynomial in d, provided delta is fixed and d…

Algebraic Geometry · Mathematics 2012-08-24 Florian Block

Kontsevich's formula for rational plane curves is a recursive relation for the number $N_d$ of degree $d$ rational curves in $\mathbb{P}^2$ passing through $3d-1$ general points. We provide two proofs of this recursion: the first more…

Algebraic Geometry · Mathematics 2025-10-17 Greg Weiler

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

Let X be a (possibly nodal) K-trivial threefold moving in a fixed ambient space P. Suppose X contains a continuous family of curves, all of whose members satisfy certain unobstructedness conditions in P. A formula is given for computing the…

Algebraic Geometry · Mathematics 2007-05-23 Herbert Clemens , Holger P. Kley

Given an ordered sequence of $N$-choose-2 integers, we give necessary and sufficient conditions to have an ordered collection of $N$ simple closed curves on a torus such that the algebraic pairwise intersections of those curves are the…

Geometric Topology · Mathematics 2025-08-25 Ferit Öztürk

A new, simple method to approach enumerative questions about rational curves on rational surfaces is described. Applications include a short proof of Kontsevich's formula for plane curves and a the solution of the analogous problem for the…

alg-geom · Mathematics 2008-02-03 Lucia Caporaso , Joe Harris

This note presents a formula for the enumerative invariants of arbitrary genus in toric surfaces. The formula computes the number of curves of a given genus through a collection of generic points in the surface. The answer is given in terms…

Algebraic Geometry · Mathematics 2007-05-23 Grigory Mikhalkin