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Mediators are used for integration of heterogeneous information sources. We present a system for declaratively specifying mediators. It is targeted for integration of sources with unstructured or semi-structured data and/or sources with changing schemas. We illustrate the main features of the Mediator Specification Language (MSL), show how they facilitate integration, and describe the implementation of the system that interprets the MSL specifications.

The past five years have seen dramatic advances in planning algorithms, with an emphasis on propositional methods such as Graphplan and compilers that convert planning problems into propositional CNF formulae for solution via systematic or stochastic SAT methods. Related work on the Deep Space One spacecraft control algorithms advances our understanding of interleaved planning and execution. In this survey,we explain the latest techniques and suggest areas for future research.

Since its inception, artificial intelligence has relied upon a theoretical foundation centred around perfect rationality as the desired property of intelligent systems. We argue, as others have done, that this foundation is inadequate because it imposes fundamentally unsatisfiable requirements. As a result, there has arisen a wide gap between theory and practice in AI, hindering progress in the field. We propose instead a property called bounded optimality. Roughly speaking, an agent is bounded-optimal if its program is a solution to the constrained optimization problem presented by its architecture and the task environment. We show how to construct agents with this property for a simple class of machine architectures in a broad class of real-time environments. We illustrate these results using a simple model of an automated mail sorting facility. We also define a weaker property, asymptotic bounded optimality (ABO), that generalizes the notion of optimality in classical complexity th...

This paper presents an analysis of purpose clauses in the context of instruction understanding. Such analysis shows that goals affect the interpretation and / or execution of actions, lends support to the proposal of using generation and enablement to model relations between actions, and sheds light on some inference processes necessary to interpret purpose clauses.

Artificial intelligence researchers have been designing representation systems for default and abductive reasoning. Logic Programming researchers have been working on techniques to improve the efficiency of Horn Clause deduction systems. This paper describes how one such default and abductive reasoning system (namely Theorist) can be translated into Horn clauses (with negation as failure), so that we can use the clarity of abductive reasoning systems and the efficiency of Horn clause deduction systems. We thus show how advances in expressive power that artificial intelligence workers are working on can directly utilise advances in efficiency that logic programming researchers are working on. Actual code from a running system is given. 1 Introduction Many people in Artificial Intelligence have been working on default reasoning and abductive diagnosis systems [35, 20, 4, 29]. The systems implemented so far (eg., [1, 16, 12, 34, 32]) are only prototypes or have been developed in A Theo...

Causal reconstruction is the task of reading a written causal description of a physical behavior, forming an internal model of the described activity, and demonstrating comprehension through question answering. This task is difficult because written descriptions often do not specify exactly how referenced events fit together. This article (1) characterizes the causal reconstruction problem, (2) presents a representation called transition space, which portrays events in terms of "transitions," or collections of changes expressible in everydaylanguage, and (3) describes a program called PATHFINDER, which uses the transition space representation to perform causal reconstruction on simplified English descriptions of physical activity.PATHFINDER works byidentifying partial matches between the representations of events and using these matches to form causal chains, fill causal gaps, and merge overlapping accounts of activity. By applying transformations to events prior to matching, PATHFINDER is also able to handle a range of discontinuities arising from a writer's use of analogy or abstraction.

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The world of business and organised work is changing. This change is driven by a shift of organisational focus away from individual fragmented tasks toward an examination of the holistic processes. New tools are being developed to assist individuals in building, evaluating, and managing these processes. The application of these tools though must be holistic as well. Organisational knowledge management should be structured in a way that encourages exchange of process knowledge. In order to e ectively share information, we believe theremust be an explicit account ofwhat knowledge will be exchanged, a shared understanding. We approach thisbyproviding an extensible ontology which presents process related concepts and terminology which are common to a range of applications and industries.

. In an experimental setting of mechanical-object assembly, the CODY ##Concept Dynamics"# project is concerned with the development of knowledge representations and inference methods that are able to dynamically conceptualize the situation in the task environment. A central aim is to enable an arti#cial agentto understand and process natural-language instructions of a human partner. Instructions may build on the current perception of the assembly environment on the one hand, and on the other on the knowledge-based understanding of grouped structures in the developing construct. To this end, a dynamic conceptualization must integrate information not only describing the types of the objects involved, but also their changing functional roles when becoming part of structured assemblies. Wehave developed an operational knowledge representation formalism, COAR ##Concepts for Objects, Assemblies, and Roles"#, by which processes of dynamic conceptualization in sequences of assembly steps can...