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Generation N: 2
01234560123456
AbObcbcOAAcaac-[0] = 7
AbcbcbcOAAcaab-[1] = 8
AaNbbbaNcNaacc-[2] = 3
ANNbabbOONbbcc-[3] = 3
AcNbcbbAONbbcc-[4] = 4
AbAccbcOAAcaac-[5] = 7
NaObaccOAbbcca-[6] = 4
AbObcbcOAacaac-[7] = 6
AbabbbcOAacaab-[8] = 6
AbObcbbOAacaac-[9] = 6
Figure 3.7. The second generation of computer programs evolved to solve the
Majority( a , b , c ) function problem. The individuals of this generation are the
immediate descendants of the selected individuals of the previous generation.
Note that a perfect program with maximum fitness was discovered (chromosome 1),
thus better than all its ancestors.
solution to the majority function. As it is shown by its expression in Figure 3.8,
this perfect solution involves a total of 11 nodes, two more nodes than the
most parsimonious solutions to the majority function problem that can be
designed using the primitives AND, OR, and NOT.
Let's now take a closer look at the event that led to the creation of this
perfect solution. By comparing its genome with the genomes of all the indi-
viduals of the previous generation, there is no doubt that this new individual
is a direct descendant of the best individual of generation 1, chromosome 6:
a.
0123456
AbcbcbcOAAcaab
0123456
b.
O
A
O
c
b
A
A
c
a
a
b
Figure 3.8. A perfect solution to the majority function. a) The chromosome
encoding two sub-ETs linked by OR. b) The perfect solution encoded in the
chromosome (the linking function is shown in gray).
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