English

Polar degrees and closest points in codimension two

Algebraic Geometry 2019-08-16 v2

Abstract

Suppose that XAPn1X_A\subset \mathbb{P}^{n-1} is a toric variety of codimension two defined by an (n2)×n(n-2)\times n integer matrix AA, and let BB be a Gale dual of AA. In this paper we compute the Euclidean distance degree and polar degrees of XAX_A (along with other associated invariants) combinatorially working from the matrix BB. Our approach allows for the consideration of examples that would be impractical using algebraic or geometric methods. It also yields considerably simpler computational formulas for these invariants, allowing much larger examples to be computed much more quickly than the analogous combinatorial methods using the matrix AA in the codimension two case.

Keywords

Cite

@article{arxiv.1711.02381,
  title  = {Polar degrees and closest points in codimension two},
  author = {Martin Helmer and Bernt Ivar Utstøl Nødland},
  journal= {arXiv preprint arXiv:1711.02381},
  year   = {2019}
}

Comments

25 pages, 1 figure

R2 v1 2026-06-22T22:38:28.963Z