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The best-of-generation models (chromosomes 13 and 19) have an R-square
of 0.01346 and a fitness of 376.9933 and, therefore, are better (in terms of
fitness alone) than the best program of the previous generation. The plots for
the target and predicted values are shown in Figure 6.6.
0.9
0.8
Target
0.7
Model
0.6
0.5
0.4
0.3
0.2
0.1
0.0
-1.0
-0.5
0.0
0.5
1.0
Figure 6.6. Comparison of the target function (6.1) with one of the best models of
generation 1 (chromosome 19; see its expression in Figure 6.5). It has a fitness of
376.9933 and an R-square of 0.01346.
It's worth noticing that these best-of-generation individuals are direct de-
scendants of the best individual of the previous generation. In fact, chromo-
some 19 codes not only for the same ADFs but also for a cell that is exactly
the same - Cell 1 - which, interestingly, was the best cell in the parental chro-
mosome. Thus, thanks to a small point mutation in the homeotic gene 0, the
focus shifted from Cell 1 to Cell 0 , which now codes for the best or active cell.
In the next generation there was no improvement in best fitness and the
best ten individuals of this generation are all descendants of either chromo-
some 13 or 19 of the previous generation:
Generation N: 2
0123456789001234567890012345678012345678
*aa++aaaaaa-**/+aaaaaa+0*-11110**-011010,0-[ 0] = 376.9933
-**-+aaaaaa--*/*aaaaaa+0*-01010**/010010,1-[ 1] = 0
*aa++aaaaaa-**/+aaaaaa0+*-11010**-011010,0-[ 2] = 376.9933
 
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