Randi？ Index of Benzenoid Systems and Phenylenes

Sa？etak A new parameter, related to and easily determined from the structure of a benzenoid system and that of a phenylene - the number of inlets (r) - is introduced. The connectivity (Randi？) index of both benzenoid systems and phenylenes is then shown to depend solely on the number of vertices and on r. A simple relation is established between the connectivity index of a phenylene and of the corresponding hexagonal squeeze. Analogous relations are reported for the edge-connectivity indices