No abstract

Abstract. This paper describes T OY, an implementation of a Constraint Functional Logic Programming scheme CF LP (C), where C is a coordination domain involving the cooperation among several constraint domains D1, ..., Dn via a mediatorial domain M . This implementation follows a cooperative goal solving calculus for CF LP (C) based on lazy narrowing, invocation of solvers for each domain Di, and projection operations for converting Di constraints into Dj constraints with the aid of mediatorial constraints supplied by M . Mediatorial constraints allow solving programs that require constraints of different domains, and projection may improve performance, allowing certain solvers to profit from (the projected forms) of constraints originally intended for other solvers. As a relevant concrete instance of our CF LP (C), we implemented the cooperation among Herbrand, real arithmetic and finite domain constraints, and the mediatorial constraints relate numeric variables belonging to the last two domains. These mediatorial constraints are the bridge #== :: int -> real -> bool (that evaluates to true if their arguments are equivalent -i.e., the real value is considered to represent the integer one-and false otherwise), and the antibridge #/== :: int -> real -> bool (with a countermeaning).

This paper presents a computational model for the cooperation of constraint domains and an implementation for a particular case of practical importance. The computational model supports declarative programming with lazy and possibly higher-order functions, predicates, and the cooperation of different constraint domains equipped with their respective solvers, relying on a so-called constraint functional logic programming (CFLP) scheme. The implementation has been developed on top of theCFLPsystem, supporting the cooperation of the three domains ℋ, ℛ, and ℱ, which supply equality and disequality constraints over symbolic terms, arithmetic constraints over the real numbers, and finite domain constraints over the integers, respectively. The computational model has been proved sound and complete w.r.t. the declarative semantics provided by theCFLPscheme, while the implemented system has been tested with a set of benchmarks and shown to behave quite efficiently in comparison to the closest related approach we are aware of.

This paper presents a computational model for the cooperation of constraint domains, based on a generic Constraint Functional Logic Programming (CF LP ) Scheme and designed to support declarative programming with functions, predicates and the cooperation of different constraint domains equipped with their respective solvers. We have developed an implementation in the CF LP system T OY, supporting an instance of the scheme which enables the cooperation of symbolic Herbrand constraints, finite domain integer constraints, and real arithmetic constraints. We provide a theoretical result and an analysis of benchmarks showing a good performance with respect to the closest related approach we are aware of.

No abstract