A note on performance guarantees for sequencing three-stage flexible flowshops with identical machines to minimize makespan

In this note a tight worst-case ratio bound is derived for a heuristic for the three-stage flexible flowshop makespan minimization problem. It is shown that the derived bound is the best available for the three-stage problem. Furthermore, the derived bound can be used to improve the best available worst-case ratio bound for the flexible flowshop makespan minimization problem with an arbitrary odd number of stages.