English

Disjointness Graphs of segments in $R^2$ are almost all Hamiltonian

Combinatorics 2023-04-07 v2

Abstract

Let PP be a set of n2n\geq 2 points in general position in R2R^2. The edge disjointness graph D(P)D(P) of PP is the graph whose vertices are all the closed straight line segments with endpoints in PP, two of which are adjacent in D(P)D(P) if and only if they are disjoint. In this note, we give a full characterization of all those edge disjointness graphs that are hamiltonian. More precisely, we shall show that (up to order type isomorphism) there are exactly 8 instances of P for which D(P)D(P) is not hamiltonian. Additionally, from one of these 8 instances, we derive a counterexample to a criterion for the existence of hamiltonian cycles due to A. D. Plotnikov in 1998.

Keywords

Cite

@article{arxiv.2303.16700,
  title  = {Disjointness Graphs of segments in $R^2$ are almost all Hamiltonian},
  author = {J. Leaños and Christophe Ndjatchi and L. M. Ríos-Castro},
  journal= {arXiv preprint arXiv:2303.16700},
  year   = {2023}
}