Choice number and energy of graphs Original Research Article

The energy of a graph G, denoted by E(G), is defined as the sum of the absolute values of all eigenvalues of the adjacency matrix of G. It is proved that image for every graph G of order n, and that E(G)greater-or-equal, slanted2ch(G) for all graphs G except for those in a few specified families, where image, χ(G), and ch(G) are the complement, the chromatic number, and the choice number of G, respectively.