a. Topology Index Histograms shown for the V. cholerae Chr. I genome, where the x-axes are the topology index, and the y-axes show the event counts (i.e., occurance of that particular topolgy index in the genome). The topology index is computed by the following scheme: (i) initialize index for all bases in sequesnce to zero. (ii) Each base in a forward sense ORF, with length greater than a specified cut-off, is incremented by +10,000 for each such ORF overlap. Similarly, bases in reverse sense ORFs are incremented by +1,000 for each such overlap. Voids larger than the cut-off length in the non-standard smORFs each give rise to an increment of +1. The figure shows that V. cholerae only has a small portion of its genome involved in multiple gene encodings. b. Shows a close-up view of the 10000 topology index peak.