Improving the Global Constraint SoftPrec

  • Authors:

  • David Lesaint;Deepak Mehta;Barry O'Sullivan;Luis Quesada;Nic Wilson

  • Affiliations:

  • British Telecommunications plc, UK, david.lesaint@bt.com;Cork Constraint Computation Centre, University College Cork, Ireland, {d.mehta|b.osullivan|l.quesada|n.wilson}@4c.ucc.ie;Cork Constraint Computation Centre, University College Cork, Ireland, {d.mehta|b.osullivan|l.quesada|n.wilson}@4c.ucc.ie;Cork Constraint Computation Centre, University College Cork, Ireland, {d.mehta|b.osullivan|l.quesada|n.wilson}@4c.ucc.ie;Cork Constraint Computation Centre, University College Cork, Ireland, {d.mehta|b.osullivan|l.quesada|n.wilson}@4c.ucc.ie

  • Venue:
  • Proceedings of the 2010 conference on ECAI 2010: 19th European Conference on Artificial Intelligence
  • Year:
  • 2010

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Abstract

A soft global constraint SOFTPREC has been proposed recently for solving optimisation problems involving precedence relations. In this paper we present new pruning rules for this global constraint. We introduce a pruning rule that improves propagation from the objective variable to the decision variables, which is believed to be harder to achieve. We further introduce a pruning rule based on linear programming, and thereby make SOFTPREC a hybrid of constraint programming and linear programming. We present results demonstrating the efficiency of the pruning rules.