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456
Towards a Declarative Query and Transformation Language for XML and Semistructured Data: Simulation Unification
, 2002
"... The growing importance of XML as a data interchange standard demands languages for data querying and transformation. Since the mid 90es, several such languages have been proposed that are inspired from functional languages (such as XSLT [1]) and/or database query languages (such as XQuery [2]). ..."
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Cited by 90 (37 self)
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The growing importance of XML as a data interchange standard demands languages for data querying and transformation. Since the mid 90es, several such languages have been proposed that are inspired from functional languages (such as XSLT [1]) and/or database query languages (such as XQuery [2]). This paper addresses applying logic programming concepts and techniques to designing a declarative, rule-based query and transformation language for XML and semistructured data.
Constraint propagation
- Handbook of Constraint Programming
, 2006
"... Constraint propagation is a form of inference, not search, and as such is more ”satisfying”, both technically and aesthetically. —E.C. Freuder, 2005. Constraint reasoning involves various types of techniques to tackle the inherent ..."
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Cited by 77 (5 self)
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Constraint propagation is a form of inference, not search, and as such is more ”satisfying”, both technically and aesthetically. —E.C. Freuder, 2005. Constraint reasoning involves various types of techniques to tackle the inherent
The K.U.Leuven CHR system: implementation and application
- First Workshop on Constraint Handling Rules: Selected Contributions
, 2004
"... We present the K.U.Leuven CHR system: what started out as a validation of a new attributed variables implementation, has become a part of three different Prolog systems with an increasing userbase. ..."
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Cited by 66 (38 self)
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We present the K.U.Leuven CHR system: what started out as a validation of a new attributed variables implementation, has become a part of three different Prolog systems with an increasing userbase.
A theory of overloading
- ACM Transactions on Programming Languages and Systems (TOPLAS
, 2002
"... Abstract We introduce a novel approach for debugging ill-typed programs in the Hindley/Milner system. We map the typing problem for a program to a system of constraints each attached to program code that generates the constraints. We use reasoning about constraint satisfiability and implication to f ..."
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Cited by 65 (21 self)
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Abstract We introduce a novel approach for debugging ill-typed programs in the Hindley/Milner system. We map the typing problem for a program to a system of constraints each attached to program code that generates the constraints. We use reasoning about constraint satisfiability and implication to find minimal justifications of type errors, and to explain unexpected types that arise. Through an interactive process akin to declarative debugging, a user can track down exactly where a type error occurs. We are able to capture various extensions of the Hindley/Milner system such as type annotations and Haskell-style type class overloading. The approach has been implemented as part of the Chameleon system.
The Refined Operational Semantics of Constraint Handling Rules
- UNDER CONSIDERATION FOR PUBLICATION IN THEORY AND PRACTICE OF LOGIC PROGRAMMING
, 2003
"... Constraint Handling Rules (CHRs) are a high-level rule-based 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 ..."
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Cited by 59 (5 self)
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Constraint Handling Rules (CHRs) are a high-level rule-based 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 the theoretical operational semantics, but is still non-deterministic (from the user’s perspective). This paper formally defines this refined operational semantics and proves it implements the theoretical operational semantics. It also shows how to create a (partial) confluence checker capable of detecting programs which are confluent under this semantics, but not under the theoretical operational semantics. This supports the use of new idioms in CHR programs.
The Computational Power and Complexity of Constraint Handling Rules
- In Second Workshop on Constraint Handling Rules, at ICLP05
, 2005
"... Constraint Handling Rules (CHR) is a high-level rule-based programming language which is increasingly used for general purposes. We introduce the CHR machine, a model of computation based on the operational semantics of CHR. Its computational power and time complexity properties are compared to thos ..."
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Cited by 56 (23 self)
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Constraint Handling Rules (CHR) is a high-level rule-based programming language which is increasingly used for general purposes. We introduce the CHR machine, a model of computation based on the operational semantics of CHR. Its computational power and time complexity properties are compared to those of the well-understood Turing machine and Random Access Memory machine. This allows us to prove the interesting result that every algorithm can be implemented in CHR with the best known time and space complexity. We also investigate the practical relevance of this result and the constant factors involved. Finally we expand the scope of the discussion to other (declarative) programming languages.
Information Integration Using Contextual Knowledge and Ontology Merging
, 2003
"... With the advances in telecommunications, and the introduction of the Internet, information systems achieved physical connectivity, but have yet to establish logical connectivity. Lack of logical connectivity is often inviting disaster as in the case of Mars Orbiter, which was lost because one team u ..."
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Cited by 52 (7 self)
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With the advances in telecommunications, and the introduction of the Internet, information systems achieved physical connectivity, but have yet to establish logical connectivity. Lack of logical connectivity is often inviting disaster as in the case of Mars Orbiter, which was lost because one team used metric units, the other English while exchanging a critical maneuver data. In this Thesis, we focus on the two intertwined sub problems of logical connectivity, namely data extraction and data interpretation in the domain of heterogeneous information systems. The first challenge, data extraction, is about making it possible to easily exchange data among semi-structured and structured information systems. We describe the design and implementation of a general purpose, regular expression based Caméléon wrapper engine with an integrated capabilities-aware planner/optimizer/executioner. The second challenge, data interpretation, deals with the existence of heterogeneous contexts, whereby each source of information and potential receiver of that information may operate with a different context, leading to large-scale semantic heterogeneity. We extend the existing formalization of the COIN framework with new logical formalisms and features to handle larger
Analyses, Optimizations and Extensions of Constraint Handling Rules
, 2005
"... This is a summary of the Ph.D. thesis of Tom Schrijvers [4]. Constraint Handling Rules (CHR) [3] is a rule-based language commonly embedded in a host language. It combines elements of Constraint Logic Pro-gramming and term rewriting. Several implementations of CHR exist: in Prolog, Haskell, Java and ..."
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Cited by 52 (26 self)
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This is a summary of the Ph.D. thesis of Tom Schrijvers [4]. Constraint Handling Rules (CHR) [3] is a rule-based language commonly embedded in a host language. It combines elements of Constraint Logic Pro-gramming and term rewriting. Several implementations of CHR exist: in Prolog, Haskell, Java and HAL. Typical applications of CHR are in the area of constraint solving, but currently CHR is also used in a wider range of applications, such as type checking, natural language processing and multi-agent systems. In this work we contribute program analyses, program optimizations and extensions of the CHR language. For the optimized compilation of CHR we present several new optimiza-tions: code specialization for ground constraints, anti-monotonic delay avoid-ance, hashtable constraint stores and a new late storage optimization. These and other optimizations have been implemented in a new state-of-the-art CHR system: the K.U.Leuven CHR system [5] which is currently available in SWI-
Specification and Verification of Agent Interaction Protocols in a Logic-based System
- PROCEEDINGS OF THE 2004 ACM SYMPOSIUM ON APPLIED COMPUTING (SAC)
, 2004
"... In multiagent systems, agent interaction is ruled by means of interaction protocols. Compliance to protocols can be hardwired in agent programs; however, this requires that only “certified ” agents interact. In open societies, composed of autonomous and heterogeneous agents whose internal structure ..."
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Cited by 49 (9 self)
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In multiagent systems, agent interaction is ruled by means of interaction protocols. Compliance to protocols can be hardwired in agent programs; however, this requires that only “certified ” agents interact. In open societies, composed of autonomous and heterogeneous agents whose internal structure is, in general, not accessible, interaction protocols should be specified in terms of the agent observable behaviour, and compliance should be verified by an external entity. In this paper, we propose a Java-Prolog-CHR system for verification of compliance of agents ’ behaviour to protocols specified in a logic-based formalism (Social Integrity Constraints). We also present the application of the formalism and the system to the specification and verification of the FIPA Contract-Net protocol.
Compliance verification of agent interaction: a logic-based tool
- Applied Artificial Intelligence
, 2006
"... In open societies of agents, where agents are autonomous and heterogeneous, it is not realistic to assume that agents will always act so as to comply to interaction protocols. Thus, the need arises for a formalism to specify constraints on agent interaction, and for a tool able to observe and check ..."
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Cited by 47 (24 self)
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In open societies of agents, where agents are autonomous and heterogeneous, it is not realistic to assume that agents will always act so as to comply to interaction protocols. Thus, the need arises for a formalism to specify constraints on agent interaction, and for a tool able to observe and check for agent compliance to interaction protocols. In this paper we present a Java-Prolog software component which can be used to verify compliance of agent interaction to protocols written in a logicbased formalism (Social Integrity Constraints). 1
