Two-stage no-wait hybrid flow shop scheduling with inter-stage flexibility: A mathematical model

This paper presents a time-indexed mixed integer linear programming model for two-stage no-wait hybrid flow shop scheduling with inter-stage flexibility. Approximate algorithms as well as lower bounds are also developed. Moreover, we propose valid inequalities in order to strengthen the mixed integer linear programming model. The suggested approaches are tested on randomly generated instances based on realistic data for operating room scheduling. Experimental results on the performance of the model and valid inequalities are reported. The quality of the heuristics is also assessed for the different sizes of instance classes. The results obtained from the heuristics show overall good quality average gaps from the best found solutions.