Molecular graphs basic subgraphs

Another application of basic subgraphs arises from the possibility of relating the invariants of molecular graphs to the occurrence numbers of some basic subgraphs. Estrada has developed this methodology for spectral moments of the edge-adjacency matrix of molecular graphs - defined as the traces of the different powers of such matrix ... 

Overall connectivity indices vere proposed as a meaningful measure of topological complexity of molecules, since they satisfy two fundamental requirements to a complexity measure to increase with both the number of structural elements and their intercoimectedness the basic idea is that The higher the connectivity of molecular graph and its connected subgraphs, the more complex the molecule [Bonchev and Trinajstic, 1977]. 

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