Page 49 - 49A Field Guide to Genetic Programming

4.2 Step-by-Step Sample Run 35

4.2.4 Termination and Solution Designation
Because the fitness of the individual in Figure 4.3d is below 0.1, the termina-
tion criterion for the run is satisfied and the run is automatically terminated.
This best-so-far individual (Figure 4.3d) is then designated as the result of
the run.
Note that the best-of-run individual (Figure 4.3d) incorporates a good
2
trait (the quadratic term x ) from the first parent (Figure 4.1b) with two
other good traits (the linear term x and constant term of 1) from the second
parent (Figure 4.1a). The crossover operation thus produced a solution to
this problem by recombining good traits from these two relatively fit parents
into a superior (indeed, perfect) offspring.
This is, obviously, a highly simplified example, and the dynamics of a
real GP run are typically far more complex than what is presented here.
Also, in general, there is no guarantee that an exact solution like this will
be found by GP.