具有固定直径单圈图的Estrada指标
The Estrada index of unicyclic graphs with fixed diameter

针对具有固定直径的奇单圈图类中Estrada指标的最大图，通过不断缩小它所在的范围，证明了Δdn是具有固定直径的奇单圈图类中Estrada指标最大的唯一图. 其中，Δdn表示在三角形的一个顶点粘上n－d－2条悬挂边和一条长为d2的路，另一个顶点粘上一条长为d2－1的路所得到的图.
In view of the unique graph with maximum Estrada index among the odd unicyclic graphs with fixed diameter，make the range of it narrow. In this paper we show that Δdn is the unique graph with maximum Estrada index among the odd unicyclic graphs with fixed diameter. Let Δdn be the graph which is obtained from a triangle by attaching n－d－2 pendant edges and a path of length d2 at one vertex of it，and a path of length d2－1 to another vertex，respectively