Sparse universal graphs for planarity
arXiv:2010.05779 · doi:10.1112/jlms.12781
Abstract
We show that for every integer there exists a graph with vertices and edges such that every -vertex planar graph is isomorphic to a subgraph of . The best previous bound on the number of edges was , proved by Babai, Chung, Erdős, Graham, and Spencer in 1982. We then show that for every integer there is a graph with vertices and edges that contains induced copies of every -vertex planar graph. This significantly reduces the number of edges in a recent construction of the authors with Dujmović, Gavoille, and Micek.
v4: minor change. v3: revised following referee's comments. v2: added new result about induced-universal graphs