A hypocoloring model for batch scheduling

  • Authors:
  • D. de Werra;M. Demange;J. Monnot;V. Th. Paschos

  • Affiliations:
  • Ecole Polytechnique Fédérale de Lausanne, EPFL, Switzerland;ESSEC, Department of SID, France;LAMSADE CNRS, Université Paris-Dauphine, Place de Marechal de Lattre de Tassigny, Paris, Cedex 75775, France;LAMSADE CNRS, Université Paris-Dauphine, Place de Marechal de Lattre de Tassigny, Paris, Cedex 75775, France

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2005

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Abstract

Starting from a batch scheduling problem, we consider a weighted subcoloring in a graph G; each node v has a weight w(v); each color class S is a subset of nodes which generates a collection of node disjoint cliques. The weight w(S) is defined as max{w(K)=@?"v"@?"Kw(v)|K@?S}. In the scheduling problem, the completion time is given by @?"i"="1^kw(S"i) where S=(S"1,...,S"k) is a partition of the node set of graph G into color classes as defined above. Properties of such colorings concerning special classes of graphs (line graphs of cacti, block graphs) are stated; complexity and approximability results are presented. The associated decision problem is shown to be NP-complete for bipartite graphs with maximum degree at most 39 and triangle-free planar graphs with maximum degree k for any k=3. Polynomial algorithms are given for graphs with maximum degree two and for the forests with maximum degree k. An (exponential) algorithm based on a simple separation principle is sketched for graphs without triangles.