Constraint Handling Rules (CHR) is a high-level language commonly used to write constraint solvers. Most CHR programs depend on the refined operational semantics, resulting in an obfuscated logical reading and non-termination or worse under the theoretical operational semantics. We introduce a source to source transformation called guard simplification which allows CHR programmers to write self...

CHR is usually compiled to high-level languages (like Prolog) that make it hard or impossible to express low-level optimizations. This is a pity, because it confines CHR to be a prototyping language only, with an unacceptable performance for production quality software. This paper presents CCHR, a CHR system embedded in the C programming language, that compiles to low-level C code which is high...

Transformation provided definitive evidence for linkage between tyrB282::Tn551 ermB321 and omega (Chr::Tn551)34, and thus between the separate large linkage groups containing these markers, in Staphylococcus aureus NCTC 8325. Transformation also defined the chromosomal loci for the purC193::Tn551 and omega (Chr::Tn551)42 markers and the linkage of a tetracycline resistance marker (tet-3490) wit...

In this exploratory paper we introduce CHR¬, an extension of the CHR language with negation as absence, an established feature in production rule systems. Negation as absence is a procedural notion that allows a more concise and clean programming style. We propose a formal operational semantics for CHR¬ close to CHR’s refined operational semantics. We illustrate and motivate its properties with...

• The goal of treatment for those at CHR is not just on preventing conversion to psychosis but ameliorating the wide range of problems with which these young people present.1 The majority of these CHR individuals are indeed clinical cases. Not only are they troubled by the attenuated psychotic symptoms which define their “at risk state” but the majority have comorbid diagnoses in particular dep...

Cepharanthine, a bisbenzylisoquinoline (biscoclaurine) alkaloid, completely overcomes resistance of a multidrug-resistant subline, ChR-24, derived from human KB carcinoma cells, to vincristine, actinomycin D, and daunomycin, and partially overcomes resistance to Adriamycin. Another biscoclaurine alkaloid, berbamine, partially overcomes resistance to these anticancer agents. Accumulation of [3H]...

We introduce the notion of connuence for Constraint Handling Rules (CHR), a powerful language for writing constraint solvers. With CHR one simpliies and solves constraints by applying rules. Connuence guarantees that a CHR program will always compute the same result for a given set of constraints independent of which rules are applied. We give a decidable, suucient and necessary syntactic condi...

We introduce the notion of connuence for Constraint Handling Rules (CHR), a powerful language for writing constraint solvers. With CHR one simpliies and solves constraints by applying rules. Connuence guarantees that a CHR program will always compute the same result for a given set of constraints independent of which rules are applied. We give a decidable, suucient and necessary syntactic condi...

We introduce the notion of connuence for Constraint Handling Rules (CHR), a powerful language for writing constraint solvers. With CHR one simpliies and solves constraints by applying rules. Connuence guarantees that a CHR program will always compute the same result for a given set of constraints independent of which rules are applied. We give a decidable, suucient and necessary syntactic condi...

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 ...