We propose a framework which extends Antitonic logic Programs [Damásio and Pereira, in: Proc. 6th Int. Conf. on logic programming and Nonmonotonic Reasoning, Springer, 2001, p. 748] to an arbitrary complete bilat...
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From the granular computing perspective, the existing notions of validity, confidence, and coverage of rules in approximation spaces may be viewed as too crisp since granularity of the space is not, in general, taken ...
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In order to address problems encountered in the design of rule-based and expert systems the paper discusses a proposal of a new approach to rule-based system design and verification using an integrated CASE tool suppo...
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In order to address problems encountered in the design of rule-based and expert systems the paper discusses a proposal of a new approach to rule-based system design and verification using an integrated CASE tool supporting visual design of rule-based systems. The Mirella tool allows for dynamic on-line specification of components of the knowledge with simultaneous analysis of the rule-based system during the design phase. The main idea is to move the design procedure to a more abstract, logical level, where knowledge specification is based on use of abstract rule representation, called extended Tabular Trees, supported by Mirella CASE tool. It consists of visual design environment integrated with Prolog-based analysis and verification engine. Along with editor's built in on-line checking capabilities it improves system performance and safety. Selected implementation aspects are also highlighted. The environment is implemented in ANSI C in the GNU/Linux environment using Gtk/GNOME/SWI-Prolog development platform. This makes it both efficient and portable. The tool has a multilayer, multimodule architecture which gives it flexibility and allows future extensions.
One of the most difficult problems in Multi-Agent Systems (MAS) involves representing the knowledge and beliefs of an agent which performs its tasks in a dynamic environment. New perceptions modify this agent's cu...
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One of the most difficult problems in Multi-Agent Systems (MAS) involves representing the knowledge and beliefs of an agent which performs its tasks in a dynamic environment. New perceptions modify this agent's current knowledge about the world, and consequently its beliefs about it also change. Such a revision and update process should be performed efficiently by the agent, particularly in the context of real-time constraints. In the last decade argumentation has evolved as a successful approach to formalize defeasible, commonsense reasoning, gaining wide acceptance in the MAS community by providing tools for designing and implementing features, which characterize reasoning capabilities in rational agents. In this paper we present a new argument-based formalism specifically designed for representing knowledge and beliefs of agents in dynamic environments, called Observation-based Defeasible logic programming (ODeLP). A simple but effective perception mechanism allows an ODeLP-based agent to model new incoming perceptions, and modify the agent's knowledge about the world accordingly. In addition, in order to improve the reactive capabilities of ODeLP-based agents, the process of computing beliefs in a changing environment is made computationally attractive by integrating a "dialectical database" with the agent's program, providing pre-compiled information about previous inferences. We present algorithms for managing dialectical databases as well as examples of their use in the context of real-world problems.
At present, the search for specific information on the World Wide Web is faced with several problems, which arise on the one hand from the vast number of information sources available, and on the other hand, from thei...
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At present, the search for specific information on the World Wide Web is faced with several problems, which arise on the one hand from the vast number of information sources available, and on the other hand, from their intrinsic heterogeneity, since standards are missing. A promising approach for solving the complex problems emerging in this context is the use of multi-agent systems of information agents, which cooperatively solve advanced information-retrieval problems. This requires advanced capabilities to address complex tasks, such as search and assessment of information sources, query planning, information merging and fusion, dealing with incomplete information, and handling of inconsistency. In this paper, our interest lies in the role which some methods from the field of declarative logic programming can play in the realization of reasoning capabilities for information agents. In particular, we are interested to see how they can be used, extended, and further developed for the specific needs of this application domain. We review some existing systems and current projects, which typically address information-integration problems. We then focus on declarative knowledge-representation methods, and review and evaluate approaches and methods from logic programming and nonmonotonic reasoning for information agents. We discuss advantages and drawbacks, and point out the possible extensions and open issues.
In the paper, a simplified six degrees of freedom mathematical model encompassing calm water maneuvering and traditional seakeeping theories is developed to simulate the ship turning circle test in regular waves. A co...
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In the paper, a simplified six degrees of freedom mathematical model encompassing calm water maneuvering and traditional seakeeping theories is developed to simulate the ship turning circle test in regular waves. A coordinate system called the horizontal body axes system is used to present equations of maneuvering motion in waves. All corresponding hydrodynamic forces and coefficients for seakeeping are time varying and calculated by strip theory. For simplification, the added mass and damping coefficients are calculated using the constant draft but vary with encounter frequency. The nonlinear mathematical model developed here is successful in simulating the turning circle of a containership in sea trial conditions and can be extended to make the further simulation for the ship maneuvering under control in waves.
Decidability of definitional equality and conversion of terms into canonical form play a central role in the meta-theory of a type-theoretic logical framework. Most studies of definitional equality are based on a conf...
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Decidability of definitional equality and conversion of terms into canonical form play a central role in the meta-theory of a type-theoretic logical framework. Most studies of definitional equality are based on a confluent, strongly normalizing notion of reduction. Coquand has considered a different approach, directly proving the correctness of a practical equivalance algorithm based on the shape of terms. Neither approach appears to scale well to richer languages with, for example, unit types or subtyping, and neither provides a notion of canonical form suitable for proving adequacy of encodings. In this article, we present a new, type-directed equivalence algorithm for the LF type theory that overcomes the weaknesses of previous approaches. The algorithm is practical, scales to richer languages, and yields a new notion of canonical form sufficient for adequate encodings of logical systems. The algorithm is proved complete by a Kripke-style logical relations argument similar to that suggested by Coquand. Crucially, both the algorithm itself and the logical relations rely only on the shapes of types, ignoring dependencies on terms.
In order to be able to succinctly describe properties of systems based on the infinitesimal-step-width approach to modelling timed systems, a novel notation for a temporal logic is developed. It uses two types of term...
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ISBN:
(纸本)3540255761
In order to be able to succinctly describe properties of systems based on the infinitesimal-step-width approach to modelling timed systems, a novel notation for a temporal logic is developed. It uses two types of terms: focused terms are interpreted over positions in a system behavior, and interval terms are interpreted over intervals. The logic is similar to the Duration Calculus with respect to its operators. An extension is the "bar term" in which two interval terms are combined into a focused term, and another extension are rule predicates. Another specialty of our approach is that the semantic domain over which the formulas are interpreted contains not just the state sequence of a system behavior, but the sequence of actions which lead to the state sequence. The notation is rich enough to express important predicates of other temporal logics. Important concepts of reactive systems can be formalized: weak and strong fairness and limited activity. An application of the notation to a problem of modelling synchronous systems in our time model is given, which proves limited activity of a synchronous system.
Much work has been done on extending the well-founded semantics to general disjunctive logic programs and various approaches have been proposed. However, these semantics are different from each other and no consensus ...
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Mobile agent development is mainly supported by Java-based platforms and tools. However, the weak mobility model they use, the lack of adequate support for developing inference and reasoning mechanisms, added to the i...
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Mobile agent development is mainly supported by Java-based platforms and tools. However, the weak mobility model they use, the lack of adequate support for developing inference and reasoning mechanisms, added to the inherent complexity of building location-aware software, impose strong limitations for developing mobile intelligent agent systems. In this article we present MoviLog, a platform for building Prolog-based mobile agents with a strong mobility model. MoviLog is an extension of JavaLog, an integration of Java and Prolog, that allows us to take advantage of the best features of the programming paradigms they represent. MoviLog agents, called Brainlets, are able to migrate among different Web sites, either proactively or reactively, to use the available knowledge in order to find a solution. The major contribution of MoviLog is its Reactive Mobility by Failure (RMF) mechanism. RMF is a mechanism that acts when an agent needs a resource or service that is not available at the current executing site. RMF uses a distributed multi-agent system to transparently transport the executing agent to the site where the resource/service is available, thus reducing the development effort with respect to the traditional mobile agent approach, while maintaining its advantages.
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