A speed-up method for calculating total flowtime in permutation flow shop scheduling problem

Permutation flow shop scheduling problem with total flowtime criterion has been increasingly dealt with in recent years. A number of heuristics and metaheuristics have been developed for this problem. However, the calculation of total flow time for job permutations spends too much computational time in the algorithms. To address to this problem, Li et al [OMEGA, 2009, 37:155-164] presented a general flowtime computing method and proved its effectiveness. This paper proposes an improvement for the general flowtime computing method. The computation experiments based on the well-known benchmarks are provided. It is shown that the presented speed-up method is of effectiveness for the problem considered.