Page 108 - Data Science Algorithms in a Week

92 Fred K. Gruber

Figure 15. Effect of the different crossover type on the standard deviation.

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The 4-parent diagonal crossover has the highest fitness function at the 20
generation; however, it has a higher standard deviation than the two-point crossover (see
Figure 15 and Table 4). In order to make a decision we use a technique found in Law and
Kelton (2000) for finding the best of k systems. With this methodology, we selected the
diagonal crossover as the best for this particular problem.

Effect of Varying Mutation Rates

Four ways to set the mutation rate are tested: fixed mutation rate, dynamically
adapted, self-adaptation, and feedback. The other parameters are kept constant: diagonal
crossover with 4 parents, crossover rate of 0.95 and tournament selection. For the fixed
mutation rate, the probability of mutation is set to 0.05. The behavior of the average best
fitness as a function of the generation is shown in Figure 16. Figure 17 shows the
behavior of the standard deviation.