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

Read full text
Authors: Gaiane Yu. Panina, Dirk Siersma
Cited by: 0

Abstract

We prove the following results: (1) For every generic closed smooth curve in $\mathbb{R}^3$, {whose torsion has a constant sign}, there is a point with at least $6$ emanating normals to the curve. If the curve is knotted, and torsion has a constant sign, there is a point with at least $8$ emanating normals. (2) For every generic closed piecewise linear curve in $\mathbb{R}^3$ there is a point with at least $8$ emanating normals to the curve {(no condition on the torsion)}. If the curve is knotted, then there is a point with at least $10$ emanating normals. The proof is based on the Morse theory for the squared distance function and self intersections of the focal surface.

Fields of Study & Subjects

Geometric and Algebraic Topology Advanced Differential Geometry Research Geometric Analysis and Curvature Flows

Publication details

Journal / source
arXiv (Cornell University)
Publication date
6 February 2026
Document type
Preprint