Nordhaus-gaddum-type relations for the energy and Laplacian energy of graphs


B. Zhou, I. Gutman


Let $\overline{G}$ denote the complement of the graph $G$ . If $I(G)$ is some invariant of $G$ , then relations (identities, bounds, and similar) pertaining to $I(G)+I(\overline{G})$ are said to be of Nordhaus-Gaddum type. A number of lower and upper bounds of Nordhaus-Gaddum type are obtained for the energy and Laplacian energy of graphs. Also some new relations for the Laplacian graph energy are established.