色多项式与图的平面性

Chromatic Polynomials and Planarity of Graphs

设图Ｇ的色多项式为Ｐ（Ｇ，λ），α＿１（Ｇ）是Ｐ（Ｇ，λ）中λ项的系数的绝对值。本文证明了：若１≤α＿１（Ｇ）≤２３，则图Ｇ是连通的平面图。

Let P(G,λ)denote the chromatic polynomial of a graph G, α1(G) is absolutevalues of the coefficients of λ in P(G,λ).If 1≤α1(G)≤23, graph G is the connected planar graph is proved.