From the Connectivity Index to Various RandiC-Type Descriptors

The Randie index was proposed by Rancho in 1975 and has been widely studied in different areas. We briefly review the Randle index and various Randietype descriptors from 1975 to date, including higher-order Rancho' indices, zeroth order Randle indices, D-L-S generalization, sum-connectivity indices, geometric arithmetic indices, harmonic index, atom-bond connectivity index, Balaban index, Randie matrix, Randie spectrum, Randie energy, etc. We also point out some important applications of the various Randie-type indices.