图G的k全染色是用k种颜色对图G的V(G)∪E(G)中的元素进行着色,使得相邻或者相关联的两个元素染不同的颜色,图G的全色数是使G存在k全染色的最小整数k.对最大度为Δ的平面图,如果(1)Δ(G)≥5且任何点至多关联一个长度至多为5的圈,或者(2)Δ≥4,不含3圈并且任何点至多关联一个长度至多为6的圈,则它的全色数为Δ(G)+1。
A total k-coloring of a graph G is acoloring of V(G) UE(G) using k colors such that no two adjacent or incident elements receive the same color. The total chromatic number of G is the smallest integer k such that G has a total k-coloring. It is proved here that the total chromatic number of a planar graph G is (1)Δ(G)≥5and every vertex is incident with at most one cycle of length at most 5, or (2)Δ≥4, the girth g≥4 and every vertex is incident with at most one cycle of length at most 7.