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