Off-line temporary tasks assignment

  • Authors:
  • Yossi Azar;Oded Regev;Jirí Sgall;Gerhard J. Woeginger

  • Affiliations:
  • Department of Computer Science, Tel-Aviv University, Tel-Aviv 69978, Israel;Department of Computer Science, Tel-Aviv University, Tel-Aviv 69978, Israel;Mathematical Inst., AS CR, Zitná 25, CZ-11567 Praha 1, Czech Republic;Inst, für Mathematik, TU Graz, Steyrergasse 30, A-8010 Graz, Austria

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2002

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Abstract

In this paper we consider the temporary tasks assignment problem. In this problem, there are m parallel machines and n independent jobs. Each job has an arrival time, a departure time and some weight. Each job should be assigned to one machine. The load on a machine at a certain time is the sum of the weights of jobs assigned to it at that time. The objective is to find an assignment that minimizes the maximum load over machines and time.We present a polynomial time approximation scheme for the case in which the number of machines is fixed. We also show that for the case in which the number of machines is given as part of the input (i.e., not fixed), no polynomial algorithm can achieve a better approximation ratio than 3/2 unless P = NP.