Infeasibility Testing and Repairing Algorithms for Job Shop Scheduling

The issue of the feasibility or infeasibility of constraints is important and sometimes is more fundamental than optimization itself. The job shop scheduling problem (JSSP) is one of the hardest combinatorial optimization problems. However, the feasibility study for JSSP is still an undeveloped area. In this paper, we present an intuitive method to diagnose the feasibility of a solution of the job shop scheduling problem. A theorem, guaranteeing the correctness of the method, is proved. Furthermore an intuitive and fast repairing algorithm is developed to reach feasibility from infeasible solutions of the problem.