GA. However, they need to be updated because an RPN

ome is no longer a string of binary values. Before introducing how

ding operators work for a GP problem, two RPN strings are

They are x3y*+xz++ for ݔ൅3ݕ൅ݔݖ and 5xy**zy*+ for

ݕ. Figure 8.7 shows two RPN chromosomes for these two

s.

Fig. 8.7. Two RPN chromosomes for two equations.

PN chromosome is only one way of expression of an equation.

tion can also be visualised by a tree. Figure 8.8 shows two tree

ns for the RPN chromosomes shown in Figure 8.7.

(a) (b)

wo tree expressions of the RPN chromosomes shown in Figure 8.7. (a) The tree

er panel RPN in Figure 8.7. (b) The tree for the lower panel RPN in Figure 8.7.

A, a chromosome is a string of binary values, therefore a mutation

or a crossover operation is much easier to implement. For

the use of the mutation operator will turn over between zero and

ome bits of a chromosome to change the presence and absence

the candidate variables. However, an RPN chromosome is not

d of binary values. Instead, each entry is either a variable, or a

or an operator, or a bracket if a more complicated equation is