Abstract
Local search methods are effective for solving scheduling problems in the case where the computation time is limited. However, the performance of the local search methods depends on the definition of neighborhood, that is, the procedure to generate new solutions. In this paper, a local search method with new neighborhood structures is proposed for job shop scheduling problems of minimizing the makespan. The solution in the proposed method is represented by an operation sequence. In this representation a same schedule is generated generally from different operation sequences, and such redundancy reduces the search efficiency. The proposed neighborhood structures generate necessarily a schedule which is different from the incumbent one. Moreover, two neighborhood structures based on this idea are used by turns for escaping from a local optimum. The proposed method is applied to some benchmark problems. It is shown from the computational results that the proposed method outperforms other local search methods.
