A Modified Symbiotic Organisms Search Algorithm Applied to Flow Shop Scheduling Problems

The Symbiotic Organism Search (SOS) algorithm is an optimization metaheuristic inspired by the symbiotic relationships that occur among organisms in nature. In the last few years, the SOS algorithm attracted increasing attention due to its good performance on various real-world problems, despite the fact that no specific parameter adjustment is required. In this paper, we propose an improved version of SOS by modifying the organisms selection strategy. In the proposed version of the algorithm, three organisms are selected from the population without having a predefined symbiotic relationship. Once the organisms are selected, an assignment step is conducted to assign each organism to a symbiotic relationship. We tested the performance of the proposed algorithm using twenty benchmark instances of the flow shop scheduling problem. We compared the results with the results obtained using the original SOS algorithm. The proposed modification improved the performance of the SOS algorithm in the search for the global optimum value in most of the instances.