A Survey of Constraint Transformation Methods

Abstract

The solution performance of finite domain (FD) constraint problems can often be improved by either transforming particular constraints or sub-problems into other FD constraints like binary, table or regular membership constraints, or by transformation of the complete FD problem into an equivalent problem but of another domain, e.g. in a SAT problem. Specialized constraint solvers (like binary or SAT solvers) can outperform general constraint solvers for certain problems. However, this comes with high efforts for the transformation and/or other disadvantages such as a restricted set of constraints such specialized solvers can handle or limitations on the variables domains. In this paper we give an overview of CSP and constraint transformations and discuss applicabilibty and advantages and disadvantages of these approaches.