More on the laplacian estrada index

Abstract

Let G be a graph with n vertices and let μ1, μ2, ... , μn be its Laplacian eigenvalues. In some recent works a quantity called Laplacian Estrada index was considered, defined as LEE(G) =. We now establish some further properties of LEE, mainly upper and lower bounds in terms of the number of vertices, number of edges, and the first Zagreb index.