Linear notation for benzenoid aromatic hydrocarbons. Molecular similarity based on notation similarity

Two succinct linear notation systems to encode the structure of polybenzenoid aromatic hydrocarbons are exemplified. Both notation systems use a labeled dual inner graph to represent the hydrocarbon. A molecular similarity index ranging from unity (identical molecules) to zero (completely different molecules) is defined based on a comparison of the linear notations for a pair of compounds. The similarity index procedure is applied to a correlation of the carcinogenic properties of the benzenoid hydrocarbons.