English

Plane Spanning Trees in Edge-Colored Simple Drawings of $K_n$

Computational Geometry 2020-08-21 v1 Discrete Mathematics

Abstract

K\'{a}rolyi, Pach, and T\'{o}th proved that every 2-edge-colored straight-line drawing of the complete graph contains a monochromatic plane spanning tree. It is open if this statement generalizes to other classes of drawings, specifically, to simple drawings of the complete graph. These are drawings where edges are represented by Jordan arcs, any two of which intersect at most once. We present two partial results towards such a generalization. First, we show that the statement holds for cylindrical simple drawings. (In a cylindrical drawing, all vertices are placed on two concentric circles and no edge crosses either circle.) Second, we introduce a relaxation of the problem in which the graph is kk-edge-colored, and the target structure must be hypochromatic, that is, avoid (at least) one color class. In this setting, we show that every (n+5)/6\lceil (n+5)/6\rceil-edge-colored monotone simple drawing of KnK_n contains a hypochromatic plane spanning tree. (In a monotone drawing, every edge is represented as an xx-monotone curve.)

Keywords

Cite

@article{arxiv.2008.08827,
  title  = {Plane Spanning Trees in Edge-Colored Simple Drawings of $K_n$},
  author = {Oswin Aichholzer and Michael Hoffmann and Johannes Obenaus and Rosna Paul and Daniel Perz and Nadja Seiferth and Birgit Vogtenhuber and Alexandra Weinberger},
  journal= {arXiv preprint arXiv:2008.08827},
  year   = {2020}
}

Comments

Appears in the Proceedings of the 28th International Symposium on Graph Drawing and Network Visualization (GD 2020)