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455
Bellman goes Relational
 In ICML
, 2004
"... Motivated by the interest in relational reinforcement learning, we introduce a novel relational Bellman update operator called ReBel. It employs a constraint logic programming language to compactly represent Markov decision processes over relational domains. ..."
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Cited by 45 (3 self)
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Motivated by the interest in relational reinforcement learning, we introduce a novel relational Bellman update operator called ReBel. It employs a constraint logic programming language to compactly represent Markov decision processes over relational domains.
The CIFF Proof Procedure for Abductive Logic Programming with Constraints
 In Proceedings JELIA04
, 2004
"... We introduce a new proof procedure for abductive logic programming and present two soundness results. Our procedure extends that of Fung and Kowalski by integrating abductive reasoning with constraint solving and by relaxing the restrictions on allowed inputs for which the procedure can operate ..."
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Cited by 43 (20 self)
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We introduce a new proof procedure for abductive logic programming and present two soundness results. Our procedure extends that of Fung and Kowalski by integrating abductive reasoning with constraint solving and by relaxing the restrictions on allowed inputs for which the procedure can operate correctly. An implementation of our proof procedure is available and has been applied successfully in the context of multiagent systems.
Optimizing Compilation of Constraint Handling Rules
, 2001
"... CHRs are a multiheaded 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 discuss the optimizing compilation of Constraint Handling Rul ..."
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Cited by 40 (7 self)
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CHRs are a multiheaded 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 discuss the optimizing compilation of Constraint Handling Rules (CHRs). In particualr, we show how we can use dierent kinds of information in the compilation of CHRs in order to obtain access eciency, and a better translation of the CHR rules into the underlying language. The kinds of information used include the types, modes, determinism, functional dependencies and symmetries of the CHR constraints. We also show how to analyze CHR programs to determine information about functional dependencies, symmetries and other kinds of information supporting optimizations.
An Experimental CLP Platform for Integrity Constraints and Abduction
 In Proceedings of FQAS2000, Flexible Query Answering Systems: Advances in Soft Computing series
, 2000
"... Integrity constraint and abduction are important in queryanswering systems for enhanced query processing and for expressing knowledge in databases. A straightforward characterization of the two is given in a subset of the language CHR _ , originally intended for writing constraint solvers to be a ..."
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Cited by 39 (18 self)
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Integrity constraint and abduction are important in queryanswering systems for enhanced query processing and for expressing knowledge in databases. A straightforward characterization of the two is given in a subset of the language CHR _ , originally intended for writing constraint solvers to be applied for CLP languages. This subset has a strikingly simple computational model that can be executed using existing, Prologbased technology. Together with earlier results, this confirms CHR _ as a multiparadigm platform for experimenting with combinations of topdown and bottomup evaluation, disjunctive databases and, as shown here, integrity constraint and abduction 1 Introduction Constraint logic programming (CLP) [10] is established as an extension to logic programming that adds higher expressibility and in some cases more efficient query evaluation. CLP has also given rise to a field of constraint databases [14]. In the present paper, we suggest CLP techniques applied for defini...
Optimal UnionFind in Constraint Handling Rules
 UNDER CONSIDERATION FOR PUBLICATION IN THEORY AND PRACTICE OF LOGIC PROGRAMMING
, 2005
"... Constraint Handling Rules (CHR) is a committedchoice rulebased language that was originally intended for writing constraint solvers. In this paper we show that it is also possible to write the classic unionfind algorithm and variants in CHR. The programs neither compromise in declarativeness nor ..."
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Cited by 36 (24 self)
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Constraint Handling Rules (CHR) is a committedchoice rulebased language that was originally intended for writing constraint solvers. In this paper we show that it is also possible to write the classic unionfind algorithm and variants in CHR. The programs neither compromise in declarativeness nor efficiency. We study the time complexity of our programs: they match the almostlinear complexity of the best known imperative implementations. This fact is illustrated with experimental results.
Specification and verification of agent interaction using social integrity constraints
 In LCMAS’03: Logic and Communication in MultiAgent Systems. ENTCS
, 2004
"... In this paper we propose a logicbased social approach to the specification and verification of agent interaction. We firstly introduce integrity constraints about social acts (called Social Integrity Constraints) as a formalism to express interaction protocols and to give a social semantics to the ..."
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Cited by 35 (14 self)
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In this paper we propose a logicbased social approach to the specification and verification of agent interaction. We firstly introduce integrity constraints about social acts (called Social Integrity Constraints) as a formalism to express interaction protocols and to give a social semantics to the behavior of agents, focusing on communicative acts. Then, we discuss several possible kinds of verification of agent interaction, and we show how social integrity constraints can be used to verify some properties in this respect. We focus our attention on static verification of compliance of agent specifications to interaction protocols, and on runtime verification, based on agents ’ observable behavior. We adopt as a running example the NetBill security transaction protocol for the selling and delivery of information goods. 1
Automatic Generation of Constraint Propagation Algorithms for Small Finite Domains
 IN 5TH INTERNATIONAL CONFERENCE ON PRINCIPLES AND PRACTICE OF CONSTRAINT PROGRAMMING, CP'99, LNCS 1713
, 1999
"... We study here constraint satisfaction problems that are based on predefined, explicitly given finite constraints. To solve them we propose a notion of rule consistency that can be expressed in terms of rules derived from the explicit representation of the initial constraints. This notion of loca ..."
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Cited by 34 (5 self)
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We study here constraint satisfaction problems that are based on predefined, explicitly given finite constraints. To solve them we propose a notion of rule consistency that can be expressed in terms of rules derived from the explicit representation of the initial constraints. This notion of local consistency is weaker than arc consistency for constraints of arbitrary arity but coincides with it when all domains are unary or binary. For Boolean constraints rule consistency coincides with the closure under the wellknown propagation rules for Boolean constraints. By generalizing the format of the rules we obtain a characterization of arc consistency in terms of socalled inclusion rules. The advantage of rule consistency and this rule based characterization of the arc consistency is that the algorithms that enforce both notions can be automatically generated, as CHR rules. So these algorithms could be integrated into constraint logic programming systems such as ECLiPSe ...
Sound and Decidable Type Inference for Functional Dependencies
, 2004
"... 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 userprogrammable type extensions in th ..."
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Cited by 33 (15 self)
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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 userprogrammable type extensions in the context of Haskell style type classes. Here, we make use of CHRs to provide for the first time a concise result that under some sufficient conditions, functional dependencies allow for sound and decidable type inference. The sucient conditions imposed on functional dependencies can be very limiting. We show how to safely relax these conditions.
Constraints for Multimedia Presentation Generation
, 2002
"... Automatic multimedia presentation generation is applicable in a wide variety of circumstances because of its ability to adapt to di#erent presentation contexts such as hardware platforms, user expertise and user interest. The process ..."
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Cited by 33 (5 self)
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Automatic multimedia presentation generation is applicable in a wide variety of circumstances because of its ability to adapt to di#erent presentation contexts such as hardware platforms, user expertise and user interest. The process
The Complexity of Equivariant Unification
 In Proceedings of the 31st International Colloquium on Automata, Languages and Programming (ICALP 2004), volume 3142 of LNCS
"... Nominal logic is a firstorder theory of names and binding based on a primitive operation of swapping rather than substitution. Urban, Pitts, and Gabbay have developed a nominal unification algorithm that unifies terms up to nominal equality. However, because of nominal logic's equivariance pri ..."
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Cited by 32 (7 self)
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Nominal logic is a firstorder theory of names and binding based on a primitive operation of swapping rather than substitution. Urban, Pitts, and Gabbay have developed a nominal unification algorithm that unifies terms up to nominal equality. However, because of nominal logic's equivariance principle, atomic formulas can be provably equivalent without being provably equal as terms, so resolution using nominal unification is sound but incomplete. For complete resolution, a more general form of unification called equivariant unification, or "unification up to a permutation" is required. Similarly, for rewrite rules expressed in nominal logic, a more general form of matching called equivariant matching is necessary. In this paper, we study the complexity of the decision problem for equivariant unification and matching. We show that these problems are NPcomplete in general. However, when one of the terms is essentially firstorder, equivariant and nominal unification coincide. This shows that equivariant unification can be performed efficiently in many interesting common cases: for example, anypurely firstorder logic program or rewrite system can be run efficiently on nominal terms.