Scheduling unitary task systems with zero-one communication delays for quasi-interval orders

  • Authors:
  • Aziz Moukrim

  • Affiliations:
  • HeuDiaSyC UMR CNRS 6599, Université de Technologie de Compiègne, Centre de Recherches de Royallieu, BP20529, F-60205 Compiègne Cedex, France

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2003

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Abstract

The class of quasi-interval orders contains properly two rich families of precedence graphs: interval orders and a subclass of series-parallel orders. In this paper, we consider the problem of scheduling unitary task systems with zero-one communication delays in order to minimize the total elapsed time for the execution of all the tasks. This problem is known to be NP-complete on an unlimited number of processors even for interval orders. When the precedence constraints are given by a quasi-interval order G and the communication delays are locally identical (which includes the UET-UCT case), we show that an optimal static scheduling can be determined in O(n log n + e) time where n denotes the number of tasks and e denotes the number of the precedence constraints in the transitive closure of G. Some extensions are discussed for nonquasi-interval orders.