ሺݔ∗ݕ∗ݖ൅ݑ∗ݒሻ/ݓ

8.10. The tree which may need the brackets to generate an RPN string.

Mutation

breeding operator used in GP for handling RPNs is the mutation

In an RPN chromosome, only the constants, the variables and the

can be mutated. The brackets cannot be mutated. A constant can

mutated to another constant, a variable can only be mutated to

ariable and an operator can only be mutated to another operator.

11(a) shows how the mutation operator is applied to the RPN

ome at the fifth token shown in the upper panel of Figure 8.7. The

replaces the + operator by the * operator, resulting in a new

ome. Figure 8.11(b) shows the resulting tree, where the mutated

n a box with the dark box.

(a) (b)

The mutation happed to an operator. (a) Before mutation. (b) After mutation.