Circumscribing certain polygonal systems Original Research Article

Polygonal systems Pq, which consist solely of q-gons, are considered. A Pq system corresponds to a polycyclic conjugated hydrocarbon with a (chemical) formula CnHS. Relations between seven selected invariants of Pq are given. The circumscribing of Pq is explained, and the invariants of k-fold circumscribed Pq are determined. The solutions are essentially different for q = 6 and q > 6. In conclusion, two open problems concerning Pq systems are formulated.