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In this paper we introduce an agent-based framework for the diagnosis of spatially distributed technical systems, based on a suitable distributed diagnosis architecture. We implement the framework using the concepts of vivid agents and extended logic programming. To demonstrate the power of our approach, we solve a diagnosis example from the domain of unreliable datagram protocols.

In this article we describe the non-monotonic reasoning system REVISE that revises contradictory extended logic programs. We sketch the REVISE algorithm and evaluate it in the domain of digital circuits.

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In this article we formally specify and implement a diagnostic agent based on extended logic programming. Motivated by the application of decentralised diagnosis of distributed systems we develop an architecture for such agents that consists of a deliberative layer with a knowledge base, an inference machine and a reactive layer for communication and control. Throughout the layers we employ logic and logic programming to solve these tasks: the knowledge base uses extended logic programming to specify the agent's behaviour and its knowledge about the system to be diagnosed. The inference machine, which provides algorithms to compute diagnoses, as well as the reactive layer, that realises a meta interpreter for the agent behaviour, are implemented in PVM-Prolog, wich enhances standard Prolog with message passing facilities.

Recent work has pointed out that diagnosis strategies are a necessary tool for the diagnosis of complex systems. Nevertheless, though current diagnosis systems are able to use explicit system models, their representation of diagnosis strategies is only implicit. In this paper we introduce a formal meta--language to express strategic knowledge in an explicit way. This language is sufficient to formalize all strategies introduced in previous work, and extends previous diagnosis strategies by the integration of empirical knowledge and by explicit statements about dependencies between actions. We provide a declarative semantics for this language and an architecture for implementation.

. Tabling has become important to logic programming in part because it opens new application areas, such as model checking, to logic programming techniques. However, the development of new extensions of tabled logic programming is becoming restricted by the formalisms that underly it. Formalisms for tabled evaluations, such as SLG [3], are generally developed with a view to a specific set of allowable operations that can be performed in an evaluation. In the case of SLG, tabling operations are based on a variance relation between atoms. While the set of SLG tabling operations has proven useful for a number of applications, other types of operations, such as those based on a subsumption relation between atoms, can have practical uses. In this paper, SLG is reformulated in two ways: so that it can be parameterized using different sets of operations; and so that a forest of trees paradigm is used. Equivalence to SLG of the new formulation, Extended SLG or SLGX , is shown whe...

We present the basic principles and possible applications of systems capable of meta-reasoning and reflection. After a discussion of the seminal approaches, we outline our own perception of the state of the art, mainly but not only in computational logic and logic programming. We review relevat successful...

Flexible problem solving consists of the dynamic selection and configuration of problem solving methods for a particular problem type, depending on the particular problem and the goal of problem solving. In this paper, we propose an architecture that supports such flexible problem solving automatically. For this purpose, problem solving methods are described in a uniform way, by an abstract model of components, which together define the functionality of the methods. Such an abstract model is used for dynamic selection and configuration of the problem solving methods. The proposed architecture for flexible problem solving consists of well known reflection techniques: two object-meta relations, a definable naming mechanism and the axiomhood and theoremhood reflection rules. We have succeeded in using standard meta-architecture techniques to enable flexible problem solving. 1 Introduction The literature on Knowledge Engineering of the past decade has identified a number of different probl...

. Alarm correlation is a necessity in large mobile phone networks, where the alarm bursts resulting from severe failures would otherwise overload the network operators. In this paper, we describe how to realize alarm-correlation in cellular phone networks using extended logic programming which provides integrity constraints, implicit, and explicit negation. We solve different scenarios for a GSM network application using the extended logic programming system Revise. 1 Introduction Mobile networks, like the pan-European GSM networks, are growing rapidly. Alarm handling systems enable the operators to run such networks with minimal operation costs. The goal is to collect and interpret alarm messages and failure indications from the network elements without human intervention. In large networks, like the current GSM networks, the alarm vectors supplied by the network elements tend to flood the workstations of the operators especially in critical situations like the passage of a t...