Notes on constant-isomer series

Constant-isomer series are polycyclic aromatic hydrocarbon sets having equal numbers of isomers. While presenting an overview of constant-isomer series, general algebraic formulations of our previous results on polycyclic hydrocarbons are reported. Numerous interrelationships and properties of specific representatives are presented. The underlying similarity relationships covered by our topological paradigm provides the unifying framework for this paper. Formulas of constant-isomers correspond to fewer types of structures.