Graphs with two crossings are 5-choosable
arXiv:1103.1801 · doi:10.1137/11082703X
Abstract
A graph G is k-choosable if G can be properly colored whenever every vertex has a list of at least k available colors. Thomassen's theorem states that every planar graph is 5-choosable. We extend the result by showing that every graph with at most two crossings is 5-choosable.
12 pages, 4 figures