Propagating Separable Equalities in an MDD Store

We present a propagator that achieves MDD consistency for a separable equality over an MDD (multivalued decision diagram) store in pseudo-polynomial time. We integrate the propagator into a constraint solver based on an MDD store introduced in [1]. Our experiments show that the new propagator provides substantial computational advantage over propagation of two inequality constraints, and that the advantage increases when the maximum width of the MDD store increases. In [1] we proposed a width-limited multivalued decision diagram (MDD) as a general constraint store for constraint programming. We demonstrated the potential of MDD-based constraint solving by developing MDD-propagators for alldiff and inequality constraints. In this paper, we describe an MDD-propagator for the separable equality constraint that uses a pseudo-polynomial algorithm to achieve MDD consistency. We show the computational advantage of the new propagator over the existing approach of modeling equalities with two i...

• Type: Conference
• Year: 2008
• Where: CPAIOR
• Authors: Tarik Hadzic, John N. Hooker, Peter Tiedemann
• Keywords: CPAIOR 2008, MDD Consistency, MDD Store, Multivalued Decision Diagram, Operations Research