循环图的Estrada指数

Estrada index of circulant graphs

设G是一个具有个n顶点和m条边的简单连通图,A(G)是它的邻接矩阵,其特征值为λ1≥λ2≥…≥λn,图G的Estrada指数定义为EE(G)=∑ni=1eλi.利用算术几何平均不等式,得到循环图的Estrada指数的一个较为精确的上界和下界.

Let G be a simply connected graph with n vertices and m edges and A（G） be its adjacency ma-trix withλ1≥λ2≥…≥λnas its eigenvalues. The Estrada index of a graph G is defined as EE（G） =n∑i=1eλiBy using arithmetic-geometric mean inequality, a comparatively accurate upper as well as lower bound was obtained for the Estrada index of circulant graph.