Biased roulette wheel scheme

In this study, two selection schemes, pre-selection and post-selection, are implemented. The pre-selection scheme is stochastic, while the post-selection scheme is deterministic. For the pre-selection operation shown in Fig. 6.4, one of the best-known selection schemes, called the biased roulette wheel scheme (Goldberg, 1989), was used. The probability of selecting an individual from the current population X(t) is given by the following equation ... 

In roulette wheel selection, the chance of a parent being selected is directly proportional to its fitness. In the example in Fig. 8.4, from a population of 10 chromosomes with a set of fitness evaluations totalUng 80, 6 individuals are selected by the biased roulette wheel scheme, according to 6 random numbers generated from the interval of 0 and 80. 

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