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The Complexity of Flowshop and Jobshop Scheduling
M. R. Garey, D. S. Johnson and Ravi Sethi
Mathematics of Operations Research
Vol. 1, No. 2 (May, 1976), pp. 117-129
Published by: INFORMS
Stable URL: http://www.jstor.org/stable/3689278
Page Count: 13
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NP-complete problems form an extensive equivalence class of combinatorial problems for which no nonenumerative algorithms are known. Our first result shows that determining a shortest-length schedule in an m-machine flowshop is NP-complete for m ≥ 3. (For m = 2, there is an efficient algorithm for finding such schedules.) The second result shows that determining a minimum mean-flow-time schedule in an m-machine flowshop is NP-complete for every m ≥ 2. Finally we show that the shortest-length schedule problem for an m-machine jobshop is NP-complete for every m ≥ 2. Our results are strong in that they hold whether the problem size is measured by number of tasks, number of bits required to express the task lengths, or by the sum of the task lengths.
Mathematics of Operations Research © 1976 INFORMS