English

Characterization of the sphere by means of congruent support cones

Metric Geometry 2026-02-03 v3

Abstract

Let MM be a convex body and let KK be a closed convex surface KK both contained in the Euclidean space E3\mathbb{E}^3. What can we say about MM if KK encloses MM and if from all the points in KK the body MM looks the same? In this work we are going to present a result which claims that if for every two support cones CxC_x, CyC_y of MM, with apexes x,yKx,y \in K, respectively, there exists Φ\Phi in the semi direct product of the orthogonal group O(3)O(3) and E3\mathbb{E}^3 such that Cy=Φ(Cx),C_y=\Phi(C_x), and this can be done in a continuous way, then MM is a sphere.

Keywords

Cite

@article{arxiv.2502.20615,
  title  = {Characterization of the sphere by means of congruent support cones},
  author = {Efren Morales Amaya},
  journal= {arXiv preprint arXiv:2502.20615},
  year   = {2026}
}