English

Tripod configurations of curves

Differential Geometry 2021-02-16 v1

Abstract

Tripod configurations of plane curves, formed by certain triples of normal lines coinciding at a point, were introduced by Tabachnikov, who showed that C2C^2 closed convex curves possess at least two tripod configurations. Later, Kao and Wang established the existence of tripod configurations for C2C^2 closed locally convex curves. In this paper we generalize these two results, answering a conjecture of Tabachnikov on the existence of tripod configurations for all C2C^2 closed plane curves by proving existence for a generalized notion of tripod configuration. We then demonstrate the existence of the natural extensions of these tripod configurations to the spherical and hyperbolic geometries for a certain class of convex curves, and discuss an analogue of the problem for regular plane polygons.

Keywords

Cite

@article{arxiv.1408.4545,
  title  = {Tripod configurations of curves},
  author = {Eric Chen and Nick Lourie},
  journal= {arXiv preprint arXiv:1408.4545},
  year   = {2021}
}