Theory of linear and integer programming
Theory of linear and integer programming
Minimizing mean flow time in two-machine open shops and flow shops
Journal of Algorithms
Open Shop Scheduling to Minimize Finish Time
Journal of the ACM (JACM)
Preemptive Scheduling of Uniform Processor Systems
Journal of the ACM (JACM)
On Preemptive Scheduling of Unrelated Parallel Processors by Linear Programming
Journal of the ACM (JACM)
On the approximability of average completion time scheduling under precedence constraints
Discrete Applied Mathematics
Scheduling chain-structured tasks to minimize makespan and mean flow time
Information and Computation
On preemption redundancy in scheduling unit processing time jobs on two parallel machines
Operations Research Letters
How useful are preemptive schedules?
Operations Research Letters
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We consider parallel machine scheduling problems with identical machines and preemption allowed. It is shown that every such problem with chain precedence constraints and release dates and an integer-concave objective function satisfies the following integrality property : for any problem instance with integral data there exists an optimal schedule where all interruptions occur at integral dates. As a straightforward consequence of this result, for a wide class of scheduling problems with unit processing times a so-called preemption redundancy property is valid. This means that every such preemptive scheduling problem is equivalent to its non-preemptive counterpart from the viewpoint of both its optimum value and the problem complexity. The equivalence provides new and simpler proofs for some known complexity results and closes a few open questions.