图的Harary指数定义为图的所有顶点对的距离的倒数之和.刻画了在给定点数和直径的图类中,Harary指数达到最大的极图,并由此确定了Harary指数关于直径的一个上界.另外,在n阶连通图中,刻画了Harary指数达到第二大和第三大的图的结构.
The Harary index of a graph is defined as the sum of reciprocals of distances between all pairs of vertices of the graph. The graph(s) with maximum Harary index among all graphs with given order and diameter was characterized, and an upper bound for the Harary index in terms of diameter was provided. In addition, the connected graphs of order n with the second maximum and the third maximum Harary indices were characterized, respectively.