A hybrid two-stage flowshop scheduling problem

This paper considers a batch scheduling problem in a two-stage hybrid flowshop that consists of m dedicated parallel machines in stage 1 and a batch processor in stage 2. The processing time of a batch is defined as the largest processing time of the jobs contained in that batch. The criterion is to minimize the makespan, the time by which all operations of jobs have been processed. For such a problem, we present a polynomial time algorithm for the case with all jobs having the same processing time on the batch processor. An approximation algorithm with a competitive ratio 2 for the general case is also presented.