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b.
Sub-ET 1
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Sub-ET 2
Sub-ET 3
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Figure 3.34. Perfect solution to the simple problem of symbolic regression. This
program was discovered in generation 10 and has maximum fitness. a) The chromo-
some of the individual. b) The sub-ETs codified by each gene. Note that sub-ET 1
and sub-ET 2 were already present in the previous best of generation solution (see
Figure 3.33), and sub-ET 2 has an even longer pedigree, going back to the initial
population (see Figure 3.31). c) The corresponding mathematical expression after
linking with addition (the contribution of each sub-ET is shown
in brackets). Note that it matches exactly the target function (3.19).
this individual with maximum fitness codes indeed for a perfect solution to the
problem at hand, matching perfectly the target function (3.19).
So, we have seen how a random collection of random chromosomes grew
into mature programs, giving their first tentative steps in a hostile environ-
ment into which they were thrown. These highly unfit individuals were then
selected to reproduce with modification, giving birth to new individuals that
adapted quickly and incredibly well to this unchanging environment. And as
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