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Theory of Computing Systems

, Volume 56, Issue 1, pp 73–81 | Cite as

A Lower Bound on Deterministic Online Algorithms for Scheduling on Related Machines Without Preemption

  • Tomáš Ebenlendr
  • Jiří Sgall
Article

Abstract

We consider one-by-one online scheduling on uniformly related machines. The input is a sequence of machines with different speeds and a sequence of jobs with different processing times. The output is a schedule which assigns the jobs to the machines; the completion time of a machine is the sum of the processing times of jobs assigned to it divided by its speed. The objective is to minimize the maximal completion time. The jobs arrive one by one and each has to be assigned to one machine immediately and irrevocably without the knowledge of the future jobs. We prove a new lower bound of 2.564 on the competitive ratio of deterministic online algorithms for this problem, improving the previous lower bound of 2.438.

Keywords

Online algorithms Scheduling Makespan Uniformly related machines Lower bounds 

Notes

Acknowledgements

We are grateful to anonymous reviewers and György Dósa for helpful comments.

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Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  1. 1.Institute of Mathematics, AS CRPraha 1Czech Republic
  2. 2.Faculty of Mathematics and PhysicsComputer Science Inst. of Charles UniversityPraha 1Czech Republic

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