Applications of graph theory in chemistry

Graph theoretical (GT) applications in chemistry underwent a dramatic revival lately. Constitutional (molecular) graphs have points (vertices) representing atoms and lines (edges) symbolizing malent bonds. This review deals with definition. enumeration. and systematic coding or nomenclature of constitutional or steric isomers, valence isomers (especially of annulenes). and condensed polycyclic aromatic hydrocarbons. A few key applications of graph theory in theoretical chemistry are pointed out. The complete set of all poasible monocyclic aromatic and heteroaromatic compounds may be explored by a mmbination of Pauli's principle, P6lya's theorem. and electronegativities. Topological indica and some of their applications are reviewed. Reaction graphs and synthon graphs differ from constitutional graphs i n their meaning of vertices and edges and find other kinds of chemical applications. This paper ends with a review of the use of GT applications for chemical nomenclature (nodal nomenclature and related areas), coding. and information processing/storage/retrieval