Improving the Global Constraint SoftPrec

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.

Authors

• David Lesaint
• Deepak Mehta 0001
• Barry O'Sullivan
• Luis Quesada 0001
• Nic Wilson

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