Rules and Strategies for Contextual Specialization of Constraint Logic Programs

We address the problem of specializing a constraint logic program wrt a constrained atom which specifies the context of use of the program We follow an approach based on transformation rules and strategies We introduce a novel transformation rule called contextual constraint replacement to be combined with variants of the traditional unfolding and folding rules We present a general Partial Evaluation Strategy for automating the application of these rules and two additional strategies the Context Propagation Strategy which is instrumental for the application of our contextual constraint replacement rule and the Invariant Promotion Strategy for taking advantage of invariance properties of the computation We show through some examples the power of our method and we compare it with existing methods for partial deduction of constraint logic programs based on extensions of Lloyd and Shepherdson's approach.