Drawings of complete graphs in the projective plane
Combinatorics
2021-03-22 v3
Abstract
Hill's Conjecture states that the crossing number of the complete graph in the plane (equivalently, the sphere) is . Moon proved that the expected number of crossings in a spherical drawing in which the points are randomly distributed and joined by geodesics is precisely , thus matching asymptotically the conjectured value of . Let denote the crossing number of a graph in the projective plane. Recently, Elkies proved that the expected number of crossings in a naturally defined random projective plane drawing of is . In analogy with the relation of Moon's result to Hill's conjecture, Elkies asked if . We construct drawings of in the projective plane that disprove this.
Keywords
Cite
@article{arxiv.2002.02287,
title = {Drawings of complete graphs in the projective plane},
author = {Alan Arroyo and Dan McQuillan and R. Bruce Richter and Gelasio Salazar and Matthew Sullivan},
journal= {arXiv preprint arXiv:2002.02287},
year = {2021}
}