Fig 1. The difference between the values of objective function of the SGC (FSGC) and the best code (Fbest) calculated under four models with different restrictions on the genetic code structure when the polarity costs were minimized for the three codon positions individually or as the sum of costs over all these positions; GEN, the least restrictive model; NUM, the model preserving the number of codons per amino acid; BLO, the model preserving the codon block structure; DEG, the model preserving the degeneracy.
