A two-stage flexible flow shop problem with unit-execution-time jobs and batching

We study a batch-scheduling problem of unit-time jobs on a two-stage flexible flowshop. The objective functions are minimum makespan and minimum flowtime. Unlike previously studied models: (i) a general number of machines in both stages of the flowshop is allowed, and (ii) there is no restriction on the number of batches to be processed on each machine. Efficient exact dynamic programming algorithms are introduced. Extensions to the case of machine-dependent setup times are studied as well. All the proposed algorithms run in polynomial time in the number of jobs.