Extension to Pericondensed Extremal Coronoids

The approach of the preceding paragraph is extended to a systematic search for pericondensed extremal tuple coronoids. In the different steps of the strategy, which is 

For the sake of brevity we shall refer to A or B as perforable (resp. nonperforable) when A or B can (resp. cannot) be perforated in the prescribed way, viz. by g naphthalene holes. 

The algorithm stops when a benzenoid A(h+2y, n +10y) is perforable for the first time, i.e. for the smallest h = oi h= h Then A (/i,n ) represents the smallest perfect extremal tuple coronoid(s) for the chosen g value. 

In an extremal tuple coronoid characterized by A (h,n ) the invariants (h, n ) obey eqn. (58). These invariants are also compatible with eqn. (62) in the sense that h becomes equal to h on inserting = n. Now, in accord with Observation 2 of Par. 3.6.1, all the larger extremal tuple coronoids can be characterized by their invariants as A (h,n ), where h may be increased indeterminately, and is found from eqn. (58) for each h value. 

It is found by inspection that dicumovalene is nonperforable (by three naphthalene holes). Notice that the heavy-line cycle in the above depiction cannot be trespassed by any corona hole, (iv) = 1, B = Ce7H2i(iTs=24, 31) represents 43 isomers, which were generated and depict probably for the first time. The depictions are not reproduced here, but they were diecked in order to verify that exactly two of these isomers were perforable and led to the two C67H2 (h=18, n l) extremal triple coronoids, which are shown in Fig. 3. (v) h = 19, = 3, A 

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