As time goes by: Constraint Handling Rules

Sneyers, Jon; Weert, Peter Van; Schrijvers, Tom; Koninck, Leslie De

doi:10.1017/s1471068409990123

Cited by 36 publications

(41 citation statements)

References 102 publications

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“…In order to change the program execution flow, source-to-source transformations are used to facilitate a straight-forward implementation on top of existing CHR implementations whilst exploiting the optimizations of current CHR compilers [15]. The normal execution of a committed-choice CHR program can be transformed into one featuring exhaustive completion to fully explore a goal's search space [6].…”

Section: Forward Chrmentioning

confidence: 99%

Combining Forward and Backward Propagation

Zaki

Abdennadher

Frühwirth

2015

Frontiers of Combining Systems

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Abstract. Constraint Handling Rules (CHR) is a general-purpose rulebased programming language. This paper studies the forward and backward propagation of rules, and explores the combination of both execution strategies. Forward propagation transforms input to output, while backward propagation uncovers input from output. This work includes a source-to-source transformation capable of implementing a backward propagation of the rules. Furthermore with the addition of annotating trigger constraints, CHR programs can be executed in a strictlyforward, strictly-backward or combined interleaved quasi-simultaneous manner. A programmer should only write one program and then the annotated transformation empowers the multiple execution strategies. The proposed work is useful for automatic implementation of bidirectional search for any search space through the combined execution strategies. Moreover, it is advantageous for reversible bijective algorithms (such as lossless compression/decompression), requiring only one algorithm direction to be implemented.

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Section: Forward Chrmentioning

confidence: 99%

Combining Forward and Backward Propagation

Zaki

Abdennadher

Frühwirth

2015

Frontiers of Combining Systems

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“…CHR defines the processing of multisets of constraints by the specification of multi-headed simplification or propagation rules. Thus, CHR is a high-level language to specify and implement constraint solvers for various application domains (see [10,27] for more detailed surveys).…”

Section: Motivationmentioning

confidence: 99%

“…More details about the concept and implementation of CHR can be found in the surveys [10,27] and the CHR website 1 . A CHR program describes the processing of a multiset of user-defined constraints (also called the constraint store) by two kinds of rules.…”

Section: Constraint Handling Rulesmentioning

confidence: 99%

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CHR(Curry): Interpretation and Compilation of Constraint Handling Rules in Curry

Hanus

2015

Practical Aspects of Declarative Languages

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Abstract. Constraint Handling Rules (CHR) is a rule-based language to specify application-oriented constraint solvers. CHR requires a host language that provides the basic constraints used in a CHR program. In this paper, we argue that an integrated functional logic language like Curry is an appropriate host language for CHR since it supports a natural formulation of constraint handling rules and a seamless integration into a typed environment. As a proof of concept, we describe CHR(Curry), an integration of CHR into Curry, together with two implementations. The first is an interpreter of CHR's refined operational semantics implemented in Curry, and the second compiles CHR rules into Prolog which can be directly used in Prolog-based Curry implementations, such as PAKCS. MotivationFunctional logic languages [4,15] integrate the most important features of functional and logic languages in order to provide a variety of programming concepts. They support functional concepts like higher-order functions and lazy evaluation as well as logic programming concepts like non-deterministic search and computing with partial information. This combination allows better abstractions for application programming and has also led to new design patterns [1,5] as well as better abstractions in application programs such as implementing graphical user interfaces [12] or web frameworks [17]. The declarative multi-paradigm language Curry [11,18] is a modern functional logic language with advanced concepts for application programming [2,3].An important application area of declarative, and in particular, logic programming languages is constraint programming [19,22]. Since logic programming is a subset of functional logic programming, there exist various attempts to extend functional logic languages with constraint solving facilities (see [24] for a survey). For instance, Lux [21] describes an implementation of a solver for real arithmetic constraints for Curry, and the inclusion of finite domain constraints in the functional logic language TOY [20] is described in [9].An alternative to using a fixed set of constraint solvers are Constraint Handling Rules (CHR) [10]. CHR is a declarative language for specifying applicationoriented constraint systems. They are useful for applications that require specific

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“…The declarative (classical logic) semantics of CHR [199] is given in terms of the constraint theory of the host language together with the logical formulas for each rule. A simplification rule H ⇐⇒ G | B, for example, corresponds to the formula∀(G → (H ↔ ∃x.B)), where∀ quantifies over all free variables.…”

Section: Constraint Handling Rulesmentioning

confidence: 99%

Models and emerging trends of concurrent constraint programming

2013

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Concurrent Constraint Programming (CCP) has been used over the last two decades as an elegant and expressive model for concurrent systems. It models systems of agents communicating by posting and querying partial information, represented as constraints over the variables of the system. This covers a vast variety of systems as those arising in biological phenomena, reactive systems, netcentric computing and the advent of social networks and cloud computing. In this paper we survey the main applications, developments and current trends of CCP.

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As time goes by: Constraint Handling Rules

Cited by 36 publications

References 102 publications

Combining Forward and Backward Propagation

Combining Forward and Backward Propagation

CHR(Curry): Interpretation and Compilation of Constraint Handling Rules in Curry

Models and emerging trends of concurrent constraint programming

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