设G是一个具有n个顶点的简单图.矩阵Q(G)=D(G)+A(G)表示图G的无符号拉普拉斯矩阵,其中D(G)和A(G)分别表示图G的顶点度对角矩阵和邻接矩阵.图G的无符号拉普拉斯埃斯特拉达指数定义为QEE(G)=∑n i=1 eλi(G),其中λ1(G)≥λ2(G)≥…≥λh(G)是指图G的无符号拉普拉斯特征值.本文确定了具有最大的无符号拉普拉斯埃斯特拉达指数的唯一的n个顶点的单圈图.
Let G be a simple graph with n vertices. The matrix Q(G) = D(G) + A(G) denotes the signless Laplacian matrix of G, where D(G) and A(G) denote the diagonal matrix of vertex degrees and the adjacency matrix of G, respectively. The signless Laplacian Estrada index of G is defined as QEE(G) = ∑n i=1 eλi(G), where λ1(G) ≥λ2(G) ≥… λn(G) are the signless Laplacian eigenvalues of G. In this paper, the unique unicyclic graph on n vertices with the maximum signless Laplacian Estrada index is determined.