Abstract
For the single machine scheduling problem of minimizing the total completion time, Montoya Torres (J Glob Opt 27:97–103, 2003) presented a semi-online algorithm under the assumption that release dates are known in advance, and showed that it was \({\sqrt{3}}\)-competitive. However, there are flaws in the proof, and the conclusion about the competitive ratio is not correct. In this note, we show that the semi-online algorithm cannot perform better than the best non-clairvoyant online algorithm with a competitive ratio of 2.
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Montoya Torres J.R.: Competitive analysis of a better on-line algorithm to minimize total completion time on a single-machine. J. Glob. Opt. 27(1), 97–103 (2003)
Hoogeveen, J.A., Vestjens, A.P.A.: Optimal on-line algorithms for single-machine scheduling. In: Goos, G., Hartmanis, J., Leeuwen, J.V. (eds.) Integer Programming and Combinatorial Optimization, the 5th International IPCO Conference Vancouver, British Columbia, Canada, June 1996. Lecture Notes in Computer Science, vol. 1084, pp. 404–414. Springer, Berlin (1996)
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This work is supported by National Science Foundation of China (Grant No. 60934007) and Specialized Research Fund for the Doctoral Program of Higher Education (Grant No.20070248004).
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Tao, J., Chao, Z. & Xi, Y. Comments on “Competitive analysis of a better on-line algorithm to minimize total completion time on a single-machine”. J Glob Optim 49, 359–362 (2011). https://doi.org/10.1007/s10898-010-9549-1
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DOI: https://doi.org/10.1007/s10898-010-9549-1