Abstract

Let G be a graph on n vertices and lambda(1), lambda(2), ..., lambda(n) their eigenvalues. The Estrada index of G is defined as EE(G) = Sigma(n)(i=1) e(lambda i). In this paper, we obtain new upper and lower bounds on the Estrada Index of a given graph, considering numerical inequalities present in the literature. (C) 2019 Elsevier Inc. All rights reserved.