Stochastic Remainder

Once the fitness of each string has been calculated the fitnesses are scaled so that the average is equal to 1. Each string then has a number of copies of itself put forward for reproduction equal to the integer part of its fitness. The remaining decimal parts are used in a random selection process to determine which strings are put forward to fill the parent shortage. The likelihood of selection is proportional to the value of the decimal part. This method ensures that the best strings are always parents, while the poorer strings still have a non-zero chance of contributing to the next generation.