Quasi-PTAS for Scheduling with Precedences using LP Hierarchies

Author Shashwat Garg

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Shashwat Garg
  • Eindhoven University of Technology, Netherlands

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Shashwat Garg. Quasi-PTAS for Scheduling with Precedences using LP Hierarchies. In 45th International Colloquium on Automata, Languages, and Programming (ICALP 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 107, pp. 59:1-59:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


A central problem in scheduling is to schedule n unit size jobs with precedence constraints on m identical machines so as to minimize the makespan. For m=3, it is not even known if the problem is NP-hard and this is one of the last open problems from the book of Garey and Johnson. We show that for fixed m and epsilon, {polylog}(n) rounds of Sherali-Adams hierarchy applied to a natural LP of the problem provides a (1+epsilon)-approximation algorithm running in quasi-polynomial time. This improves over the recent result of Levey and Rothvoss, who used r=(log n)^{O(log log n)} rounds of Sherali-Adams in order to get a (1+epsilon)-approximation algorithm with a running time of n^O(r).

Subject Classification

ACM Subject Classification
  • Theory of computation → Scheduling algorithms
  • Approximation algorithms
  • hierarchies
  • scheduling
  • rounding techniques


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