Computer Science and Engineering, Department of


Exploring Parameterized Relational Consistency

Shant K. Karakashian, University of Nebraska - Lincoln
Robert J. Woodward, University of Nebraska - Lincoln
Berthe Y. Choueiry, University of Nebraska - Lincoln

Document Type Article

University of Nebraska–Lincoln, Computer Science and Engineering
Technical Report TR-UNL-CSE-2009-0009


Consistency properties and algorithms for achieving them are at the heart of the success of Constraint Programming. For non-binary Constraint Satisfaction Problems (CSPs), the relational-consistency property R(i,j)C of [Dechter and van Beek 1997] may add new non-binary constraints to the constraint network, thus modifying its topology. The domain-filtering properties of [Bessi`ere et al. 2008] filter the domains of the variables and leave the constraints unchanged but are restricted to combinations of two constraints. We restate the property of m-wise consistency [Gyssens 1986; J´egou 1993] as relational (∗,m)-consistency, R(∗,m)C. R(∗,m)C ensures that any tuple in a relation is consistent in every combination of m constraints. The main contributions of this document are the design of an algorithm for enforcing R(∗,m)C and the evaluation of its effectiveness in a search procedure solving CSPs. This document thus establishes the usefulness in practice of higher consistency levels in non-binary CSPs.