Constraint Logic Programming
(CLP) A programming framework based (like Prolog) on LUSH (or SLD) resolution, but in which unification has been replaced by a constraint solver. A CLP interpreter contains a Prolog-like inference engine and an incremental constraint solver. The engine sends constraints to the solver one at a time. If the new constraint is consistent with the collected constraints it will be added to the set. If it is inconsistent, it will cause the engine to backtrack.
CLP* is a variant.