We propose a generic type system for the Constraint Handling Rules (CHR), a rewriting rule language for implementing constraint solvers. CHR being a high-level extension of a host language, such as Prolog or Java, this type system is parameterized by the type system of the host language. We show the consistency of the type system for CHR w.r.t. its operational semantics. We also study the case ...

Constraint Handling Rules (CHR) is both an effective concurrent declarative constraint-based programming language and a versatile computational formalism. While conceptually simple, CHR is distinguished by a remarkable combination of desirable features: – a semantic foundation in classical and linear logic, – an effective and efficient sequential and parallel execution model – guaranteed proper...

Dans ce papier, nous introduisons une version modulaire du langage Constraint Handling Rules (CHR), appelé CHRat pour CHR modulaire avec ask et tell. Toute contrainte définie dans un composant CHRat peut être réutilisée à la fois dans les règles et les gardes d’un autre composant CHRat pour définir de nouveaux solveurs de contraintes. Contrairement aux travaux précédents sur la modularité de CH...

Constraint Handling Rules (CHR) is a concurrent, committed-choice, rule-based language. One of the first CHR programs is the classic constraint solver for syntactic equality of rational trees that performs unification [7, 4, 14]. The worst-case time (and space) complexity of this short and elegant solver so far was an open problem [8] and assumed to be polynomial. In this paper we show that und...

In this paper, we introduce a modular version of the Constraint Handling Rules language CHR, called CHRat for modular CHR with ask and tell. Any constraint de ned in a CHRat component can be reused both in rules and guards in another CHRat component to de ne new constraint solvers. Unlike previous work on modular CHR, our approach is completely general as it does not rely on an automatic deriva...

ABSTRACT. One lesson learned from practical applications is that constraints are often heterogeneous. Solving such constraints requires a collaboration of constraint solvers. In this paper, we introduce a methodology for the tight integration of CHR constraint solver programs into one such program. CHR is a high-level rule-based language for writing constraint solvers and reasoning systems. A c...

Determination of the reticulocyte hemoglobin content (CHr) provides an early measure of functional iron deficiency because reticulocytes are the earliest erythrocytes released into blood and circulate for only 1 to 2 days. The CHr in 78 patients undergoing bone marrow examination was measured to assess its clinical utility for the diagnosis of iron deficiency. Twenty-eight patients were iron de...

One lesson learned from practical constraint solving applications is that constraints are often heterogeneous. Solving such constraints requires a collaboration of constraint solvers. In this paper, we introduce a methodology for the tight integration of CHR constraint programs into one such program. CHR is a high-level rule-based language for writing constraint solvers and reasoning systems. A...

Confluence is a fundamental property of Constraint Handling Rules (CHR) since, as in other rewriting formalisms, it guarantees that the computations are not dependent on rule application order, and also because it implies the logical consistency of the program declarative view. In this paper we are concerned with proving the confluence of nonterminating CHR programs. For this purpose, we derive...