The Randić index, also known as the connectivity index, of a graph is the sum of bond contributions where and are the degrees of the vertices making bond i ~ j.
History This graph invariant was introduced by Milan Randić in 1975.. It is often used in chemoinformatics for investigations of organic compounds.
Notes
References Roberto Todeschini, Viviana Consonni (2009) "Molecular Descriptors for Chemoinformatics", Wiley-VCH, .
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