关于图的色数与围长

On Chromatic Number and Girth of a Graph

设ｆ（ｍ，ｎ）表示色数为ｍ、围长不小于ｎ的图的最小阶数．本文给出了ｆ（ｍ，ｎ）的下界．并探讨了无三角形图色数的上界．

ln the paper,the authors give the lower bound of f(m.n) and discusses the su per bound of Chromatic numbers for triangle free graphs,when f(m,n) denote the minimun number of vertices of a graph in which its chromatic namber is m and girth is no less than n.