Structure count - algebraic

A review on the topological indices can hardly be complete. We had to omit here some indices like structure count (SC) and algebraic structure count of Herndon 91) which are related with the characterization of -electron molecules. 

The difference between the even and odd Kekule structures is called algebraic structure count ASC [Wilcox Jr, 1968 Wilcox Jr, 1969] or corrected structure count CSC [Herndon, 1973a Herndon, 1974b] ... 

Dias, J.R. (1992). Algebraic Structure Count. J.Math.Chem., 9,253-260. 

Graovac, A., Juvan, M., Mohar, B. and Zerovnik, J. (1999) Computing the determinant and the algebraic structure count in polygraphs. Croat, Chem, Acta, 72, 853-867. 

Kekuld structure count and algebraic structure count... 

McClelland s formula was later improved by Gutman [77,78] who left out the empirical constant but included the algebraic structure count,... 

The so-called algebraic structure count is closely related to Kekule structures but in many cases is more difficult to evaluate. It is defined as the absolute difference of the numbers of two parities positive and negative) of Kekule structures. This algebraic structure count coincides with K G) for benzenoids, but for more general alternants it has been advocated as a more reliable measure of aromaticity than K G). Closed expressions for several special classes have been derived by Gutman et Recently Graovac et al. have formulated... 

Already in the seminal paper by Dewar and Longuet-Higgins [15], it was established that the Ai -regularity does not hold for all polycyclic conjugated n-electron systems, and that corrections for the parity of Kekule structures need to be taken into account. This became the concept of algebraic structure count [22, 23], which was later shown to be not applicable to all non-altemant conjugated hydrocarbons [24, 25]. The fortunate fact is that all Kekule structures of benzenoid hydrocarbons have the same parity [20], which has the consequences that all Kekule-structure-based models work best for benzenoid systems. Also in this... 

Gutman associated several theoretical parameters of the phenylenes with those of the analogous PAHs [40]. He showed that the algebraic structure count (ASC)... 

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