Every \(1\)-Planar Graph without \(4\)-Cycles or Adjacent \(5\)-Vertices is \(5\)-Colorable

Lili Song1, Lei Sun 1
1Department of Mathematics, Shandong Normal University Jinan 250014, China

Abstract

A graph is \(1\)-planar if it can be drawn on the plane so that each edge is crossed by at most one other edge. In this paper, we prove that every \(1\)-planar graph without \(4\)-cycles or adjacent \(5\)-vertices is \(5\)-colorable.