Chemical graph theory is a branch of mathematical chemistry which applies graph theory to mathematical modelling of chemical phenomena.^{[1]} The pioneers of the chemical graph theory are Alexandru Balaban, Ivan Gutman, Haruo Hosoya, Milan Randić and Nenad Trinajstić.^{[2]} In 1988 it was reported that several hundred researchers work in this area producing about 500 articles annually. A number of monographs have been written in the area, including the twovolume comprehensive text by Trinajstic, Chemical Graph Theory, that summarized the field up to mid1980s.^{[3]}
The adherents of the theory maintain that the properties of a chemical graph, i.e., a graphtheoretical representation of a molecule gives valuable insights into the chemical phenomena. The opponents contend that graphs play only a fringe role in chemical research.^{[4]}
