Scheduling Two Machines with Release Times

  • Authors:
  • John Noga;Steven S. Seiden

  • Affiliations:
  • -;-

  • Venue:
  • Proceedings of the 7th International IPCO Conference on Integer Programming and Combinatorial Optimization
  • Year:
  • 1999

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Abstract

We present a deterministic online algorithm for scheduling two parallel machines when jobs arrive over time and show that it is (5-√5)/2 ≅ 1.38198-competitive. The best previously known algorithm is 3/2 -competitive. Our upper bound matches a previously known lower bound, and thus our algorithm has the best possible competitive ratio. We also present a lower bound of 1.21207 on the competitive ratio of any randomized online algorithm for any number of machines. This improves a previous result of 4-2√2 ≅ 1.17157.