Gregory J. Duck

Learn More
There is no standard modelling language for constraint programming (CP) problems. Most solvers have their own modelling language. This makes it difficult for modellers to experiment with different solvers for a problem. In this paper we present MiniZinc, a simple but expressive CP modelling language which is suitable for modelling problems for a range of(More)
Constraint Handling Rules (CHRs) are a high-level rulebased programming language commonly used to write constraint solvers. The theoretical operational semantics for CHRs is highly non-deterministic and relies on writing confluent programs to have a meaningful behaviour. Implementations of CHRs use an operational semantics which is considerably finer than(More)
Constraint Handling Rules (CHRs) are a powerful rule based language for specifying constraint solvers. Critical for any rule based language is the notion of confluence, and for terminating CHRs there is a decidable test for confluence. But many CHR programs that in practice are confluent fail this confluence test. The problem is that the states that(More)
In this paper we discuss the optimizing compilation of Constraint Handling Rules (CHRs). CHRs are a multi-headed committed choice constraint language, commonly applied for writing incremental constraint solvers. CHRs are usually implemented as a language extension that compiles to the underlying language. In this paper we show how we can use different kinds(More)
Functional dependencies are a popular and useful extension to Haskell style type classes. We give a reformulation of functional dependencies in terms of Constraint Handling Rules (CHRs). In previous work, CHRs have been employed for describing user-programmable type extensions in the context of Haskell style type classes. Here, we make use of CHRs to(More)
In this paper we introduce Associative Commutative Distributive Term Rewriting (ACDTR), a rewriting language for rewriting logical formulae. ACDTR extends AC term rewriting by adding distribution of conjunction over other operators. Conjunction is vital for expressive term rewriting systems since it allows us to require that multiple conditions hold for a(More)
Program analysis is essential for the optimized compilation of Constraint Handling Rules (CHRs) as well as the inference of behavioral properties such as confluence and termination. Up to now all program analyses for CHRs have been developed in an ad hoc fashion.In this work we bring the general program analysis methodology of abstract interpretation to(More)
Constraint Handling Rules (CHRs) are a high-level committed choice programming language commonly used to write constraint solvers. While the semantic basis of CHRs allows them to extend arbitrary underlying constraint solvers, in practice, all current implementations only extend Herbrand equation solvers. In this paper we show how to define CHR programs(More)
Functional dependencies are a popular and useful extension to Haskell style type classes. In this paper, we give a reformulation of functional dependencies in terms of Constraint Handling Rules (CHRs). In previous work, CHRs have been employed for describing user-programmable type extensions in the context of Haskell style type classes. Here, we make use of(More)
Constraint Handling Rules were recently extended with userdefinable rule priorities. This paper shows how this extended language can be efficiently compiled into the underlying host language. It extends previous work by supporting rules with dynamic priorities and by introducing various optimizations. The effects of the optimizations are empirically(More)