The Fixed Job Schedule Problem with Spread-Time Constraints

We consider a generalization of the fixed job schedule problem in which each processor is available only for a prefixed time interval from the release time of the earliest task assigned to it. The problem can arise in bus driver scheduling. We show that the problem is NP-hard, and introduce polynomial procedures to determine lower bounds, dominance criteria and reductions. We also develop a branch-and-bound algorithm for obtaining the optimal solution of the problem and analyze the algorithm’s average performance in a series of computational experiments. Finally, we investigate the preemptive case and other polynomial special cases.