English

Ford Spheres in the Clifford-Bianchi Setting

Number Theory 2024-11-08 v2

Abstract

We define Ford Spheres P\mathcal{P} in hyperbolic nn-space associated to Clifford-Bianchi groups PSL2(O)PSL_2(O) for OO orders in rational Clifford algebras associated to positive definite, integral, primitive quadratic forms. For H2\mathcal{H}^2 and H3\mathcal{H}^3 these spheres correspond to the classical Ford circles and Ford spheres (these are non-maximal subsets of classical Apollonian packings). We prove the Ford spheres are integral, have disjoint interiors, and intersect tangentially when they do intersect. If we assume that OO is Clifford-Euclidean then P\mathcal{P} is also connected. We also give connections to Dirichlet's Theorem and Farey fractions. In a discussion section, we pose some questions related to existing packings in the literature.

Keywords

Cite

@article{arxiv.2409.20529,
  title  = {Ford Spheres in the Clifford-Bianchi Setting},
  author = {Spencer Backman and Taylor Dupuy and Anton Hilado and Veronika Potter},
  journal= {arXiv preprint arXiv:2409.20529},
  year   = {2024}
}