GSAT has been proven highly effective for solving certain classes of large SAT problems. It starts from a randomly generated truth assignment and tries to reduce the number of violated clauses by iteratively flipping ...
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Besides the features of a class-based object-oriented language, Java integrates concurrency via its thread-classes, allowing for a multithreaded flow of control. The concurrency model offers coordination via lock-sync...
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In this paper, we consider each of the nine principles of BDI logics as defined by Rao and Georgeff based on Bratman's asymmetry thesis, and we verify which ones are satisfied by Rao's AgentSpeak(L), a computa...
In this paper, we consider each of the nine principles of BDI logics as defined by Rao and Georgeff based on Bratman's asymmetry thesis, and we verify which ones are satisfied by Rao's AgentSpeak(L), a computable logic language inspired by the BDI architecture for cognitive agents. This is in line with Rao's original motivation for defining AgentSpeak(L): to bridge the gap between the theory and practice of BDI agent systems. In order to set the grounds for the proof, we first introduce a particular way in which to define the informational, motivational, and deliberative modalities of BDI logics for AgentSpeak(L) agents, according to its structural operational semantics (that we introduced in a recent paper). This provides a framework that can be used to investigate further properties of AgentSpeak(L) agents, contributing towards giving firm theoretical grounds for BDI agent programming.
A number of agent-oriented programming systems are based on a framework of beliefs, desires and intentions (BDI) and more explicitly on the BDI logic of Rao and Georgeff. In this logic, goals are a consistent set of d...
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ISBN:
(纸本)0909925828
A number of agent-oriented programming systems are based on a framework of beliefs, desires and intentions (BDI) and more explicitly on the BDI logic of Rao and Georgeff. In this logic, goals are a consistent set of desires, and this property is fundamental to the semantics of the logic. However, implementations based on this framework typically have no explicit representation of either desires or goals, and consequently no mechanisms for checking consistency. In this paper we address this gap between theory and practice by giving an explicit representation for a simple class of desires. The simplicity of this class makes it both straightforward and efficient to check for consistency. We provide a general framework for conflict resolution based on a preference ordering of sets of goals, and we illustrate how different rules for specifying consistent goal sets (corresponding to different preference order-ings) relate to existing commitment strategies. We also report on some implementation experiments which confirm that the cost of consistency maintenance is not significant.
Constraint logicprogramming (CLP) and Hereditary Harrop formulas (HH) are two well known ways to enhance the expressivity of Horn clauses. In this paper, we present a novel combination of these two approaches. We sho...
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Constraint logicprogramming (CLP) and Hereditary Harrop formulas (HH) are two well known ways to enhance the expressivity of Horn clauses. In this paper, we present a novel combination of these two approaches. We show how to enrich the syntax and proof theory of HH with the help of a given constraint system, in such a way that the key property of HH as a logicprogramming language (namely, the existence of uniform proofs) is preserved. We also present a procedure for goal solving, showing its soundness and completeness for computing answer constraints. As a consequence of this result, we obtain a new strong completeness theorem for CLP that avoids the need to build disjunctions of computed answers, as well as a more abstract formulation of a known completeness theorem for HH.
Computational logic systems can offer an attractive environment for developing Internet applications. They share many of the important characteristics of popular network programming tools, including dynamic memory man...
Computational logic systems can offer an attractive environment for developing Internet applications. They share many of the important characteristics of popular network programming tools, including dynamic memory management, well-behaved structure and pointer manipulation, robustness, and compilation to architecture-independent bytecode. However, in addition, computational logic systems offer some unique features such as very powerful symbolic processing capabilities, constraint solving, dynamic databases, search facilities, grammars, sophisticated meta-programming, and well understood semantics. Such features can often make it very easy to code simple *** special issue concerned with applications is the third of its kind in a journal sponsored by the Association for logicprogramming. The first appeared in 1990, and showed the potential for logicprogramming to be extended. The second issue highlighted some papers from the Practical Applications of Prolog conference that had been held. This third time, the applications are concerned with the Internet and reflect the profound impact that the Internet has had on the computing landscape.
We propose a general framework for first-order functional logicprogramming, supporting lazy functions, non-determinism and polymorphic datatypes whose data constructors obey a set C of equational axioms. On top of a ...
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We propose a general framework for first-order functional logicprogramming, supporting lazy functions, non-determinism and polymorphic datatypes whose data constructors obey a set C of equational axioms. On top of a given C, we specify a program as a set R of C-based conditional rewriting rules for defined functions. We argue that equational logic does not supply the proper semantics for such programs. Therefore, we present an alternative logic which includes W-based rewriting calculi and a notion of model. We get soundness and completeness for C-based rewriting w.r.t. models, existence of free models for all programs, and type preservation results. As operational semantics, we develop a sound and complete procedure for goal solving, which is based on the combination of lazy narrowing with unification modulo C. Our framework is quite expressive for many purposes, such as solving action and change problems, or realizing the GAMMA computation model.
Most cities in Germany regularly publish a booklet called the Mietspiegel. It basically contains a verbal description of an expert system. It allows the calculation of the estimated fair rent for a flat. By band, one ...
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Most cities in Germany regularly publish a booklet called the Mietspiegel. It basically contains a verbal description of an expert system. It allows the calculation of the estimated fair rent for a flat. By band, one may need a weekend to do this task. With our computerized version, the Munich Rent Advisor, the user just fills in a form in a few minutes, and the rent is calculated immediately. We also extended the functionality and applicability of the Mietspiegel so that the user need not answer all questions on the form. The key to computing with partial information using high-level programming was to use constraint logicprogramming. We rely on the Internet, and more specifically the World Wide Web, to provide this service to a broad user group, the citizens of Munich and the people who are planning to move to Munich. To process the answers from the questionnaire and return its result, we wrote a small simple stable special-purpose web server directly in (ECLPSe)-P-i. More than 10,000 people have used our service in the last three years. This article describes the experiences in implementing and using the Munich Rent Advisor. Our results suggest that logicprogramming with constraints can be an important ingredient in intelligent internet systems.
We apply to logicprogramming some recently emerging ideas from the field of reduction-based communicating systems. with the aim of giving evidence of the hidden interactions and the coordination mechanisms that rule ...
We apply to logicprogramming some recently emerging ideas from the field of reduction-based communicating systems. with the aim of giving evidence of the hidden interactions and the coordination mechanisms that rule the operational machinery of such a programming paradigm. The semantic framework we have chosen for presenting our results is the logic, which has the advantage of allowing a uniform treatment of goals and observations and of applying abstract categorical tools for proving the results. As main contributions, we mention the finitary presentation of abstract unification, and a concurrent and coordinated abstract semantics consistent with the most common semantics of logicprogramming. Moreover, the compositionality of the tile semantics is guaranteed by standard results, as it reduces to check that the tile systems associated to logic programs enjoy the tile decomposition property. An extension of the approach for handling constraint systems is also discussed.
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