Journal of Combinatorial Theory Series B ( IF 1.4 ) Pub Date : 2020-05-05 , DOI: 10.1016/j.jctb.2020.04.006 Zdeněk Dvořák , Daniel Král' , Robin Thomas
We settle a problem of Havel by showing that there exists an absolute constant d such that if G is a planar graph in which every two distinct triangles are at distance at least d, then G is 3-colorable. In fact, we prove a more general theorem. Let G be a planar graph, and let be a set of connected subgraphs of G, each of bounded size, such that every two distinct members of are at least a specified distance apart and all triangles of G are contained in . We give a sufficient condition for the existence of a 3-coloring ϕ of G such that for every the restriction of ϕ to H is constrained in a specified way.
中文翻译:
曲面V上的三色无三角图。对具有远距异常的平面图进行着色
通过显示存在一个绝对常数d来解决Havel的问题,如果G是一个平面图,其中每两个不同的三角形之间的距离至少为d,则G是3色的。实际上,我们证明了一个更一般的定理。令G为平面图,令是G的一组连通子图的集合,每个子图的大小是有界的,使得G的每两个不同成员至少相距指定距离,并且G的所有三角形都包含在。我们给出一个充分条件3着色的存在φ的ģ使得对于每的限制φ到ħ以指定的方式被约束。