a multi-objective bisexual reproduction genetic algorithm for ...

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The new offspring is created from an empty chromosome, and then it is inserted
alternately with genes from mother and father. Because a n-credit course will be
scheduled to n successive time-slots, successive time-slots have to be copied from
mother and father. To facilitate this, all time-slots of morning or afternoon working
sessions will be copied from the mother or father to the new offspring.
Usually the new offspring is not correct thus it needs to be repaired. If a course
has not been scheduled yet, it also needs to be scheduled. In the contrary, if a course
has been scheduled more than one time in a week, it has to be removed.
A pseudo code for crossover is given in Figure 3-20.
Crossover rate pc=0.5
Father x= a chromosome is chosen randomly from the population
Mother y= a chromosome is chosen randomly from the population (y≠x)
For each day in a week
For each working-session in [morning, afternoon]
For each classroom
If (random(100) < pc*100)
Copy afternoon time-slots of father x to afternoon time-slots of the new offspring z
Else
Copy morning time-slots of mother y to morning time-slots of the new offspring z
Mutate the new offspring z
Repair the new offspring z
Calculate fitness value for the new offspring z
Insert the new offspring z into the population in order of fitness value
FIGURE 3-20 Pseudo code for crossover
If the crossover rate pc is chosen to be 50%, the 50% of the genes from the
mother and 50% of the genes from father are copied to the new offspring.
3.6.6 Mutation
A new offspring that has just been created by crossover will be mutated with a
mutation rate. This is done via the following process: go through each gene and swap
its content with another gene in the same chromosome.