English

Pairing symmetries for Euclidean and spherical frameworks

Combinatorics 2019-06-07 v2 Metric Geometry

Abstract

In this paper we consider the effect of symmetry on the rigidity of bar-joint frameworks, spherical frameworks and point-hyperplane frameworks in Rd\mathbb{R}^d. In particular we show that, under forced or incidental symmetry, infinitesimal rigidity for spherical frameworks with vertices in XX on the equator and point-hyperplane frameworks with the vertices in XX representing hyperplanes are equivalent. We then show, again under forced or incidental symmetry, that infinitesimal rigidity properties under certain symmetry groups can be paired, or clustered, under inversion on the sphere so that infinitesimal rigidity with a given group is equivalent to infinitesimal rigidity under a paired group. The fundamental basic example is that mirror symmetric rigidity is equivalent to half-turn symmetric rigidity on the 2-sphere. With these results in hand we also deduce some combinatorial consequences for the rigidity of symmetric bar-joint and point-line frameworks.

Keywords

Cite

@article{arxiv.1906.00578,
  title  = {Pairing symmetries for Euclidean and spherical frameworks},
  author = {Katie Clinch and Anthony Nixon and Bernd Schulze and Walter Whiteley},
  journal= {arXiv preprint arXiv:1906.00578},
  year   = {2019}
}

Comments

30 pages, 5 figures

R2 v1 2026-06-23T09:38:08.675Z