English

Inscribable order types

Metric Geometry 2023-10-30 v2

Abstract

We call an order type inscribable if it is realized by a point configuration where the extreme points are all on a circle. In this paper, we investigate inscribability of order types. We first show that every simple order type with at most 2 interior points is inscribable, and that the number of such order types is Θ(4nn3/2)\Theta(\frac{4^n}{n^{3/2}}). We further construct an infinite family of minimally uninscribable order types. The proof of uninscribability mainly uses M\"obius transformations. We also suggest open problems around inscribability.

Keywords

Cite

@article{arxiv.2206.01253,
  title  = {Inscribable order types},
  author = {Michael Gene Dobbins and Seunghun Lee},
  journal= {arXiv preprint arXiv:2206.01253},
  year   = {2023}
}
R2 v1 2026-06-24T11:37:37.794Z