y

p y

p

pp

e certainly resulted in different model performance.

e 8.17 shows another two resulting trees using the dual-

ome crossover operator with the branch nodes swapped as well.

pped subunits are in the boxes with the dark background.

(a) (b)

The dual-chromosome crossover for trees shown in Figure 8.15. Both the

nd the operators are swapped. The boxes in the dark background stand for

btrees.

e 8.18 shows how two RPN chromosomes are used to generate

RPN chromosomes using the dual-chromosome crossover

with the operator tokens swapped as well.

he RPN chromosomes of the dual-chromosome crossover including the branch

rees shown in Figure 8.15. The boxes in the dark background stand for the

bunits. Both the branches (the operators) and the variables are swapped.

ngle-chromosome crossover

le-chromosome crossover operation only happens to one single