Genetic forma recombination in permutation flowshop problems

This paper analyzes different representations for permutation flowshop problems. This is done using forma analysis to assess the quality of these representations with respect to makespan optimization. Classical recombination operators are studied and empirically evaluated in this context. It is shown that the best operators work on representations in which absolute positions of tasks are relevant. Subsequently, some new operators operating on these representations are proposed. These new operators are designed to exhibit specific properties regarding implicit mutation and forma transmission. Their performance is shown to be competitive with traditional operators.