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Generation N: 0
0123456789001234567890
ONOANbbcaaaNcONcaabccc-[0] = 4
ANANbaacbbcNANOAabbcbc-[1] = 5
NNNcOacbbabONcbacbbabb-[2] = 4
ANAcbbababcNcbNbabcaab-[3] = 2
AOaObbcccacObaNOacabab-[4] = 6
OOAcOaabccaAacbNcbaccb-[5] = 5
OcbbAcccbccAAOObacbaab-[6] = 6
NbAANccbacaAbNNNbbcbbc-[7] = 2
AaONbaababcAbNNAcacaaa-[8] = 6
NOAcObaccbaAObbObcacca-[9] = 4
Generation N: 1
0123456789001234567890
AaONbaababcAbNNAcacaaa-[0] = 6
OcbbAccccacObaObacbaab-[1] = 5
AOaObaabccaAacbNacabab-[2] = 6
AOaObbccbccAAONOacabab-[3] = 8
ONOANbbcaaaNcONcaabccc-[4] = 4
OOAcOaabccaAaNONcbaccb-[5] = 5
OOAcObcccacObaNOcbaccb-[6] = 5
ANANbaacbbcNAcbAabbcbc-[7] = 3
ANANbaacbbcNANOAabbcbc-[8] = 5
OaOANbbcaaaNcONcaabccc-[9] = 5
Figure 3.26.
An initial population and its immediate descendants created, via
two-point recombination, to solve the Majority(
a
,
b
,
c
) function problem. The
chromosomes encode sub-ETs linked by OR. The perfect solution found in
generation 1 (chromosome 3) is a daughter of chromosomes 4 and 6 (shown in
bold). Their other daughter (chromosome 1) is also highlighted. Note that chromo-
some 1 is less fit than both its mothers whereas chromosome 3 surpasses them
greatly and is indeed a perfect solution to the majority function problem. The event
of two-point recombination that led to the creation of this perfect solution is
shown in Figure 3.27.
It is worth emphasizing that two-point recombination is more disruptive
than one-point recombination in the sense that it recombines the genetic
material more thoroughly, constantly destroying old building blocks and cre-
ating new ones (see the Evolutionary Studies of chapter 12 for a comparison
with the other recombinational operators). But like one-point recombina-
tion, two-point recombination has also a conservative side and is good at
swapping entire genes and ORFs. And finally, two-point recombination can
also give rise to duplicated genes if used together with gene transposition.
