单圈图Laplacian矩阵的最大和次大特征值

The largest and the second largest Laplacian matrix eigenvalues of a unicyclic graph

设G=(V,E)是一个n阶的连通单圈图,λ1(G),λ2(G)分别是图G的Laplacian矩阵的最大和次大特征值.本文讨论了单圈图的最大和次大特征值与其顶点,悬挂点个数之间的关系,将已有的结论作了改进和推广.

Let G = （V,E） be a simple oonnected unicyclic graph, λ1, （G）, λ2（G） be the largest and the second largest Laplacian eigenvalues of G , respectively. In this paper, we discuss the relation between two largest eignvalues of Laplaeain matrix of unicyclic graph and the number of vertex, pendant vertex of G . And improve some results.