Optimizing bottom-up evaluation of constraint queries

Abstract

We consider a class of constraint logic programs including negation that can be executed bottom up without constraint solving, by replacing constraints with tests and assignments. We show how to optimize the bottom-up evaluation of queries for such programs using transformations based on analysis obtained using abstract interpretation. Although the paper concentrates on a class of efficiently executable programs, the optimizations we describe are correct and applicable for arbitrary constraint logic programs. Our approach generalizes earlier work on constraint propagation.