CALCULATION OF MOLECULAR DESCRIPTORS BASED ON
VARIOUS GRAPHICAL BOND ORDERS

A review of our recent results on various molecular X'/H desciptors will be presented. The X'/X molecular descriptor of a molecular graph G was introduced by Randic as the sum of graphical bond orders X(e)/X over all edges of G. We have shown that instead of calculation of all X(e)/X's one can compute the molecular descriptor X'/X directly from (structural characteristics, like number of vertices, edges and paths, valencies of vertices, the number of independent sets of edges, etc., of G. This has been explicitly proven for X'/X where X stands for the connectivity index chi, the total number of paths P, the hyper-Wiener number R, and the Hosoya index Z.