Proper latent row

Definition 5.4 A latent row (of hexagons) in a coronoid C, where all the hexagons are in contact with, the outer perimeter of C, is called a proper latent row. Otherwise the latent row is an improper latent row (of hexagons). 

If a coronoid (or benzenoid) has only one latent row of hexagons it must obviously be a proper latent row, as is the case in Fig. 4. If there are exactly two latent rows of hexagons. 

It is clear that an improper latent row of hexagons in a coronoid (or a benzenoid) cannot occur without the presence of proper latent rows in the same system. Hence the above observation can be given a slightly sharper formulation as follows. 

Observation 5.2A coronoid C is reproducible if and only if C does not possess any proper latent row of hexagons. 

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See also in sourсe #XX -- [ ]

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