English

Counting normals to closed curves in $\mathbb{R}^3$

Differential Geometry 2026-03-02 v2

Abstract

We prove the following results: (1) For every generic closed smooth curve in R3\mathbb{R}^3 there is a point with at least 66 emanating normals to the curve. (2) For every generic closed piecewise linear curve in R3\mathbb{R}^3 there is a point with at least 88 emanating normals to the curve. If the curve is knotted, there is a point with at least 1010 emanating normals. The proof is based on the Morse theory for the squared distance function and self intersections of the focal surface.

Keywords

Cite

@article{arxiv.2602.06645,
  title  = {Counting normals to closed curves in $\mathbb{R}^3$},
  author = {Gaiane Panina and Dirk Siersma},
  journal= {arXiv preprint arXiv:2602.06645},
  year   = {2026}
}
R2 v1 2026-07-01T10:24:17.121Z