Single machine group scheduling to minimize mean flow time subject to due date constraints

This paper considers a single machine group scheduling problem. All jobs are classified into groups and the jobs within a group are processed contiguously on the machine. A sequence-independent setup time is incurred between each two consecutively scheduled groups. This paper presents a solution procedure which utilizes Smith's algorithm and a proposed modified Smith's algorithm to find an optimal job sequence and an optimal group sequence which minimizes the mean flow time of jobs subject to the constraint that no jobs are tardy. The complexity of the algorithm is shown to have a polynomial running time in the number of groups and jobs.