The type of object representing an individual. Must extend WithFitness.
The current population of individuals.
A promise that resolves to a tuple containing the two selected individuals.
Also known as fitness proportionate selection. Each individual's probability of being selected is directly proportional to its absolute fitness value. Highly fit individuals represent larger slices of the wheel, while weaker individuals represent smaller slices but still retain a non-zero probability of being chosen. *
Selects two individuals from the population using roulette wheel selection. *