On Classification of Polycyclic Conjugated Compounds

As one can see, bay regions involve three benzene rings, one of which is terminal, and the central ring is a kink ring. The presence of a bay region may not be sufficient to induce cancer because benzo[e]pyrene 

Graph theoretical characterization and computer generation of certain carcinogenic benzenoid hydrocarbons and identification of bay regions were reported by K. Balasubramanian, J. J. Kaufman, and W. S. Kosky in 1980, almost 35 years ago [28]. 

Our book, being about solved and unsolved problans in structural chentistry, induced us to select carcinogenicity as a property of benzenoid hydrocarbons to illustrate considerable variations of some of the properties of this group of compounds because there are several issues that have not been clarified and understood concerning benzenoids and their carcinogenicity. Consider a question, which we consider to be unsolved  

What are, if any, the structural factors that may answer why some benzenoids do not follow the regularity that holds for most benzenoid hydrocarbons that associates the presence of the bay regions with carcinogenicity  

Here is another speculation that could be examined more closely Are highly stable benzenoids, among which is benzo[e]pyrene, less or not carcinogenic If one writes the structural formula of benzo[e]pyrene as 

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