Genetic algorithms for the no-wait flowshop sequencing problem with time restrictions

This article deals with the no-wait flowshop problem with sequence dependent set-ups and ready times solved by an evolutionary approach. The hybrid genetic algorithm presented here addresses a new hierarchically organized complete ternary tree to represent the population that put together with a recombination plan resembles a parallel processing scheme for solving combinatorial optimization problems. Embedded in the hybrid approach, a novel recursive local search scheme, recursive arc insertion (RAI), is also proposed. The effectiveness of the local search phase is crucial given that it is responsible for about 90% of the total processing time of the algorithm. Instances with known optimal solution are used to test the new algorithm and compare it to a previously proposed heuristic approach.