Properties of optimal schedules in preemptive shop scheduling

In this work we show that certain classical preemptive shop scheduling problems with integral data satisfy the following integer preemption property: there exists an optimal preemptive schedule where all interruptions and all starting and completion times occur at integral dates. We also give new upper bounds on the minimal number of interruptions for various shop scheduling problems. © 2010 Elsevier B.V. All rights reserved.