The three stage assembly permutation flowshop scheduling problem

The assembly flowshop scheduling problem has been studied recently due to its applicability in real life scheduling problems. It arises when various fabrication operations are performed concurrently in one stage. It was firstly introduced by Lee et al. (1993) in a flowshop environment. Later, Potts et al. (1995) considered the two-stage assembly flowshop problem with m concurrent operations in the first stage and an assembly operation in the second stage with the makespan objective, they showed that the considered problem is NP-hard in the strong sense even when the number of machines in the first stage is equal to two.