English

On Hurwitz--Severi numbers

Algebraic Geometry 2016-05-23 v2

Abstract

For a point pCP2p\in CP^2 and a triple (g,d,)(g,d,\ell) of non-negative integers we define a {\em Hurwitz--Severi number} Hg,d,{\mathfrak H}_{g,d,\ell} as the number of generic irreducible plane curves of genus gg and degree d+d+\ell having an \ell-fold node at pp and at most ordinary nodes as singularities at the other points, such that the projection of the curve from pp has a prescribed set of local and remote tangents and lines passing through nodes. In the cases d+g+2d+\ell\ge g+2 and d+2g+2>d+d+2\ell \ge g+2 > d+\ell we express the Hurwitz--Severi numbers via appropriate ordinary Hurwitz numbers. The remaining case d+2<g+2d+2\ell<g+2 is still widely open.

Keywords

Cite

@article{arxiv.1604.06935,
  title  = {On Hurwitz--Severi numbers},
  author = {Yurii Burman and Boris Shapiro},
  journal= {arXiv preprint arXiv:1604.06935},
  year   = {2016}
}

Comments

Version 2: title changed and some explanations added

R2 v1 2026-06-22T13:39:19.364Z