Bounds For The Distance Estrada Index Of Graphs

The D-eigenvalues {\mu}1,{\mu}2,…,{\mu}{n} of a connected graph G are the eigenvalues of its distance matrix. The distance Estrada index of G is defined in [15] as DEE=DEE(G)=\Sigma{i=1}^n e^{{\mu}_{i}} In this paper, we give better lower bounds for the distance Estrada index of any connected graph as well as some relations between DEE(G) and the distance energy.