How to extract negative information from programs is an important issue in logicprogramming. Here we address the problem for functional logic programs, from a proof-theoretic perspective. The starting point of our wo...
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How to extract negative information from programs is an important issue in logicprogramming. Here we address the problem for functional logic programs, from a proof-theoretic perspective. The starting point of our work is CRWL (Constructor based ReWriting logic), a well established theoretical framework for functional logicprogramming, whose fundamental notion is that of non-strict non-deterministic function. We present a proof calculus, CRWLF, which is able to deduce negative information from CRWL-programs. In particular, CRWLF is able to prove 'finite' failure of reduction within CRWL.
The work reported here introduces Defeasible logicprogramming (DeLP), a formalism that combines results of logicprogramming and Defeasible Argumentation. DeLP provides the possibility of representing information in ...
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The work reported here introduces Defeasible logicprogramming (DeLP), a formalism that combines results of logicprogramming and Defeasible Argumentation. DeLP provides the possibility of representing information in the form of weak rules in a declarative manner, and a defeasible argumentation inference mechanism for warranting the entailed conclusions. In DeLP an argumentation formalism will be used for deciding between contradictory goals. Queries will be supported by arguments that could be defeated by other arguments. A query q will succeed when there is an argument A for q that is warranted, i.e. the argument A that supports q is found undefeated by a warrant procedure that implements a dialectical analysis. The defeasible argumentation basis of DeLP allows to build applications that deal with incomplete and contradictory information in dynamic domains. Thus, the resulting approach is suitable for representing agent's knowledge and for providing an argumentation based reasoning mechanism to agents.
We define XPathLog as a Datalog-style extension of XPath. XPathLog provides a clear, declarative language for querying and manipulating XML whose perspectives arc especially in XML data integration. In Our characteriz...
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We define XPathLog as a Datalog-style extension of XPath. XPathLog provides a clear, declarative language for querying and manipulating XML whose perspectives arc especially in XML data integration. In Our characterization, the formal semantics is defined wrt. an edge-labeled graph-based model, which covers the XML data model. We give a complete, logic-based characterization of XML data and the main language concept Cor XML, XPath. XPath-logic extends the XPath language with variable bindings and embeds it into first-order logic. XPathLog is then the Horn fragment of XPath-logic, providing a Datalog-style, rule-based language for querying and manipulating X M L data. The model-theoretic semantics of XPath-logic serves as the base of XPathLog as a logic-programming language, whereas also an equivalent answer-set semantics for evaluating XPathLog queries is given. In contrast to other approaches, the XPath syntax and semantics is also used for a declarative specification how the database Should be updated : when used in rule heads, XPath filters are interpreted as specifications of elements and properties Which Should he added to the database.
We present some applications of intermediate logics in the field of Answer Set programming (ASP). A brief, but comprehensive introduction to the answer set semantics, intuitionistic and other intermediate logics is gi...
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We present some applications of intermediate logics in the field of Answer Set programming (ASP). A brief, but comprehensive introduction to the answer set semantics, intuitionistic and other intermediate logics is given. Some equivalence notions and their applications are discussed. Some results on intermediate logics are shown, and applied later to prove properties of answer sets. A characterization of answer sets for logic programs with nested expressions is provided in terms of intuitionistic provability, generalizing a recent result given by Pearce. It is known that the answer set semantics for logic programs with nested expressions may select non-minimal models. Minimal models can be very important in some applications, therefore we studied them;in particular we obtain a characterization, in terms of intuitionistic logic, of answer sets which are also minimal models. We show that the logic G(3) characterizes the notion of strong equivalence between programs Under the semantic induced by these models. Finally we discuss possible applications and consequences of Our results. They clearly state interesting links between ASP and intermediate logics, which might bring research in these two areas together.
The past decade has seen dramatic growth in the application of model checking techniques to the validation and verification of correctness properties of hardware, and more recently software systems. Recently, there ha...
The past decade has seen dramatic growth in the application of model checking techniques to the validation and verification of correctness properties of hardware, and more recently software systems. Recently, there has been increasing interest in applying logicprogramming techniques to model checking in particular and verification in general. For example, table-based logicprogramming can be used as an efficient means of performing explicit model checking. Other research has successfully exploited set-based logic program analysis, constraint logicprogramming, and logic program transformation techniques to verify systems.
We consider a simple extension of logicprogramming where variables may range over goals and goals may be arguments of predicates. In this language we can write logic programs which use goals as data. We give practica...
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We consider a simple extension of logicprogramming where variables may range over goals and goals may be arguments of predicates. In this language we can write logic programs which use goals as data. We give practical evidence that, by exploiting this capability when transforming programs, we can improve program efficiency. We propose a set of program transformation rules which extend the familiar unfolding and folding rules and allow us to manipulate clauses with goals which occur as arguments of predicates. In order to prove the correctness of these transformation rules, we formally define the operational semantics of our extended logicprogramming language. This semantics is a simple variant of I-D-resolution. When suitable conditions are satisfied this semantics agrees with LD-resolution and, thus, the programs written in our extended language can be run by ordinary Prolog systems. Our transformation rules are shown to preserve the operational semantics and termination.
Binary logic programs can be obtained from ordinary logic programs by a binarizing transformation. In most cases, binary programs obtained this way are less efficient than the original programs. (Demoen, 1992) showed ...
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Binary logic programs can be obtained from ordinary logic programs by a binarizing transformation. In most cases, binary programs obtained this way are less efficient than the original programs. (Demoen, 1992) showed an interesting example of a logic program whose computational behaviour was improved when it, was transformed to a binary program and then specialized by partial deduction. The class of B-stratifiable logic programs is defined. It is shown that for every B-stratifiable logic program, binarization and Subsequent partial deduction produce a binary program which does not contain variables for continuations introduced by binarization. Such programs usually have a better computational behaviour than the original ones. Both binarization and partial deduction can be easily automated. A comparison with other related approaches to program transformation is given.
The research field of Agent-Oriented Software Engineering (AOSE) aims to find abstractions, languages, methodologies and toolkits for modeling, verifying, validating and prototyping complex applications conceptualized...
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The research field of Agent-Oriented Software Engineering (AOSE) aims to find abstractions, languages, methodologies and toolkits for modeling, verifying, validating and prototyping complex applications conceptualized as Multiagent Systems (MASs). A very lively research sub-field studies how formal methods can be used for AOSE. This paper presents a detailed survey of six logic-based executable agent specification languages that have been chosen for their potential to be integrated in our ARPEGGIO project, an open framework for specifying and prototyping a MAS. The six languages are ConGolog, AGENT-O, the IMPACT agent programming language, DyLOG, Concurrent METATEM and E-hhf. For each executable language, the logic foundations are described and an example of use is shown. A comparison of the six languages and a survey of similar approaches complete the paper, together with considerations of the advantages of using logic-based languages in MAS modeling and prototyping.
lambdaProlog is known to be well-suited for expressing and implementing logics and inference systems. We show that lemmas and definitions in such logics can be implemented with a great economy of expression. We encode...
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lambdaProlog is known to be well-suited for expressing and implementing logics and inference systems. We show that lemmas and definitions in such logics can be implemented with a great economy of expression. We encode a higher-order logic using an encoding that maps both terms and types of the object logic (higher-order logic) to terms of the metalanguage (lambdaProlog). We discuss both the Terzo and Teyjus implementations of lambdaProlog. We also encode the same logic in Twelf and compare the features of these two metalanguages for our purposes.
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