Semi-online scheduling with "end of sequence" information

Leah Epstein, Deshi Ye

Research output: Contribution to journalArticlepeer-review


We study a variant of classical scheduling, which is called scheduling with "end of sequence" information. It is known in advance that the last job has the longest processing time. Moreover, the last job is marked, and thus it is known for every new job whether it is the final job of the sequence. We explore this model on two uniformly related machines, that is, two machines with possibly different speeds. Two objectives are considered, maximizing the minimum completion time and minimizing the maximum completion time (makespan). Let s be the speed ratio between the two machines, we consider the competitive ratios which are possible to achieve for the two problems as functions of s. We present algorithms for different values of s and lower bounds on the competitive ratio. The proposed algorithms are best possible for a wide range of values of s. For the overall competitive ratio, we show tight bounds of φ + 1 ≈ 2.618 for the first problem, and upper and lower bounds of 1.5 and 1.46557 for the second problem.

Original languageEnglish
Pages (from-to)45-61
Number of pages17
JournalJournal of Combinatorial Optimization
Issue number1
StatePublished - Jul 2007

Bibliographical note

Funding Information:
D. Ye: Research was supported in part by NSFC (10601048).


  • Competitive analysis
  • Machine scheduling
  • Online algorithms
  • Uniformly related machines

ASJC Scopus subject areas

  • Computer Science Applications
  • Discrete Mathematics and Combinatorics
  • Control and Optimization
  • Computational Theory and Mathematics
  • Applied Mathematics


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