5色图包含子式K_5^-的一个简单证明

A Simple Proof of 5-Colourable Graph Containing A Minor K_5^-

Hadwiger提出如下猜想:若G是k色图,则包含子式Kk,其中k=5时等价于四色定理.本文给出了5色图的一个必要条件,即5色图包含子式K5-.

Hadwiger conjectured that a k- colourable graph contains minor Kk.. The conjecture is equvalent to the four color theorem when k = 5. In this paper, we obtain a simple proof of the following result： a 5-colourable graph contain a minor K5^-. This also possibly provided a solution to the proof of the four color theorem other than using the computer.