An algorithm based on Evolution Strategies for makespan minimization in hybrid flexible flowshop scheduling problems

This work presents an algorithm based on Evolution Strategies for solving hybrid flexible flowshop scheduling problems. The construction of the initial solution is made by two methods: random NEH heuristic and Iterated Greedy Search metaheuristic. The main search mechanism in the search space of the developed algorithm is mutation, which is based on two parameters, one related to the probability of applying each type of mutation and the other related to the number of times each type of mutation is applied. After carried out the mutation, a portion of the parent population is refined by a local search procedure based on the Iterative Improvement Insertion method. These two versions of the proposed algorithm were tested and the results are compared with the ones from literature. The results showed better solutions for a subset of instances of the problem.