How to gain the parent population size in new generation with certain crossover, mutation probability and elitism size one?

Question

For example population size is 300, crossover probability of 0.75 results in 224 chromosome's selection as parents and mutation probability of 0.005 results in 2 chromosomes to mutate. With elitism size 1, we will have 227 offspring solutions. How rest of the 73 chromosomes will be generated to complete population size of 300?

Answer 1

The common approach is to copy 73 chromosomes of the old population to complete the new one.

You could:

• simply take the 73 higher fitness chromosomes (can cause premature convergence);
• perform 73 tournament selections;
• always copy the chromosomes not involved in crossover;
• randomly select 73 chromosomes among the 300 of the old population;
• ...

The effectiveness of these strategies (meta-heuristics) greatly depends on the specific problem and you have to experiment.