A Generalized Semantics for Constraint Logic Programs

We present a simple and powerful generalized algebraic semantics for constraint logic programs that is parameterized with respect to the underlying constraint system. \Generalized semantics" abstract away from standard semantics objects, by focusing on the general properties of any (possibly non-standard) semantics deenition. In constraint logic programming, this corresponds to a suitable deenition of the constraint system supporting the semantics deenition. An algebraic structure is introduced to formalize the constraint system notion, thus making applicable classical mathematical results and both a top-down and bottom-up semantics are considered. Non-standard semantics for CLP can then be formally speciied by means of the same techniques used to deene standard semantics. Diierent non-standard semantics for constraint logic languages can be speciied in this framework: e.g. abstract interpretation, machine level traces and any computation based on an instance of the constraint system.