Recent work in Artificial Intelligence is exploring the use of formal ontologies as a way of specifying content-specific agreements for the sharing and reuse of knowledge among software entities. We take an engineering perspective on the development of such ontologies. Formal ontologies are viewed as designed artifacts, formulated for specific purposes and evaluated against objective design criteria. We describe the role of ontologies in supporting knowledge sharing activities, and then present a set of criteria to guide the development of ontologies for these purposes. We show how these criteria are applied in case studies from the design of ontologies for engineering mathematics and bibliographic data. Selected design decisions are discussed, and alternative representation choices and evaluated against the design criteria.

PROTG-II is a suite of tools and a methodology for building knowledge-based systems and domain-specific knowledge-acquisition tools. In this paper, we show how PROTG-II can be applied to the task of providing protocol-based decision support in the domain of treating HIVinfected patients. For this task, we use a problem-solving method called episodic skeletal-plan refinement. This method is decomposable; we construct it from a set of reusable components. In addition, we build an application ontology that consists of the terms and relations in the domain, plus terms that supply method-specific knowledge requirements. From this ontology, we automatically generate a domain-specific knowledge-acquisition tool. The general goal of the PROTG-II approach is to produce systems and components that are easily maintained and reusable. This is the rationale for constructing a problem-solving method from a set of smaller-grained methods and mechanisms. This is also why our knowledge-acquisition tools are domain-specific and generated automatically from ontologies. Although our evaluation is still preliminary, for the application task of providing protocol-based decision support, we show that these goals of reusability and easy maintenance can be achieved. We discuss design decisions and the tradeoffs that have to be made in the development of the system. Keywords. Decision support; expert systems; knowledge acquisition.

Assumptions of problem-solving methods refer to necessary applicability conditions of problem-solving methods, indicating that a problem-solving method is only applicable to realize a task, if the assumptions are met. In principle, such assumptions may refer to any kind of condition involved in a problem-solving method's applicability, including its required domain knowledge. In this paper, we propose a conceptual organization for assumptions of problem-solving methods and suggest a formal language to describe them. For illustration we take examples from the Propose & Revise problem-solving method and from diagnosis.

The objective of this paper is to assist the security administrators, in their attempt to specify, define and formalize security policies suited to a given high risk environment. It is then possible for the administrators to automatically derive consequencies of these policies. In particular, we want to provide users with the following functionalities: ffl Query a given security policy. ffl Verify that properties such as consistency and completeness are enforced by a given policy. ffl Verify that a given situation does not violate the security policy. ffl Investigate interoperability problems between several security policies. In this paper we more precisely focus on the problem of security policies formalization. We want to get a generic approach, being as much domain-independent as possible. In order to achieve the above goals, we have chosen a logicbased approach. It combines a deontic logic to model the concept of permission, obligation and prohibition with a modal logic of act...

The elicitation of the ontology -- i.e. the objects of a domain -- is a key issue of conceptual modelling and therefore of knowledge acquisition. The Conceptual Graph Theory provides a knowledge representation formalism to be used in knowledgebased systems with an explicit "type lattice" to account for the ontology. Since knowledge is in most AI applications non formal, it has to be normalized to ensure that the formal exploitation of its representation conforms to its meaning in the domain. Noting the intensional nature of types, which reflect the essences of the objects they denote, this normalization relies on a commitment on type definitions by necessary and sufficient conditions at the knowledge level. Our claim is that the taxonomic structure that accounts for the intensional nature of the ontology can be nothing but a tree, precluding tangled taxonomies. From this starting point, we derive methodological principles to constrain the acquisition of the "type tree", thus...

. In this paper we focus on the process of constructing reusable knowledge level models by augmenting an explicit process model of KBS design with a means of recording the argumentation about design decisions. Our method includes a set of design principles and an expressive design language for representing design components (such as tasks and roles) with an extension for decision descriptions. We present a concrete example of the application of our design methodology which illustrates how our design language can be used to produce a communicable and reusable design model. 1. INTRODUCTION It is generally accepted among researchers that knowledge engineering (KE) involves the creation of models. Van de Velde (1994b: 727) calls this the Modeling hypothesis. Since he views models as "the result of a series of arguments, negotiations and circumstances involving knowledge engineers, domain experts, clients, system developers, managers and so forth that need to agree on its acceptability fo...

. In this paper we discuss some issues concerning the organization of knowledge for reuse and we critically examine the ideas of knowledge separation and minimal ontological commitments.. Because knowledge structures can play multiple roles in a domain, it is not necessarily the case that search-control knowledge can be neatly separated from a domain ontology. This is particularly the case when only procedural descriptions of a task are available. Because expert knowledge is often `messy', clean separation of knowledge can be obtained only by removing the `troublesome' structures. However, we believe that this approach does not pay off in terms of reusability. Less knowledge means less reusability. We argue that a different approach to developing reusable ontologies is needed, which does not impose `strict' separation of knowledge, emphasizes the underlying assumptions about the available domain expertise, and does not trade knowledge for `formal purity'. These ideas are discussed in t...

This paper represents a common-kads contribution to the Sisyphus-93 experiment. This experiment is concerned with a comparison of knowledge modelling approaches. The data set for this experiment describes the knowledge for a configuring an elevator system. The ultimate goal is to arrive at standards for sharing and reusing problem-solving methods and related ontologies. 1 KNOWLEDGE MODELLING APPROACH This paper discusses a common-kads description of the Sisyphus'93 problem: the vt elevator design. The term "common-kads" is used to refer to kads as it is being developed within esprit project P5248 kads-ii. The goal of this project is to arrive at a de facto European standard for kbs development. As the term "kads" has become almost synonymous for the University of Amsterdam, it is worthwhile to point out that common-kads is the result of a cooperative effort of a number of partners, in particular also (in the context of this paper) the Free University of Brussels and the Netherlands En...

: This document is the final deliverable for task 3.5.3., Graphical User Interface and Windowing. It consists of three chapters: an analysis of the options we had and decisions which were taken, a guide describing the guidelines which support user interface design methodology, and a manual describing the primitives themselves. Author: John Domingue and Stuart Watt Collaborators (VITAL Partners): SYSECA - SYSECA TEMPS REEL (Coordinator) NOTT - UNIVERSITY OF NOTTINGHAM BULL - BULL CEDIAG AC- ANDERSEN CONSULTING ONERA - ONERA PTT - ROYAL PTT NEDERLAND NV * OU - THE OPEN UNIVERSITY NOKIA - NOKIA RESEARCH CENTER * marked partners are involved in this task Task 3.5.3 Graphical User Interface and Windowing Final Deliverable Page 2 TASK 3.5.3 GRAPHICAL USER INTERFACE AND WINDOWING FINAL DELIVERABLE INTRODUCTION This document is the written part of the final deliverable for task 3.5.3 "graphical user interface and windowing". In order for the VITAL workbench to be marketable in the 199...

This report describes the work performed by the author during an 11-months stay at the LRI (Laboratoire de Recherche en Informatique) of the University of Paris-Sud. The work has been carried out under an institutional grant (no. ERB CHBG CT 930395) of the Commission of the European Communities in the framework of the "Human Capital & Mobility" program. The project was funded under the title "Knowledge Acquisition, Validation and Explanation for Knowledge Based Systems". The work carried out touches on several research issues in Knowledge Acquisition, among which are: reuse of problemsolving methods, formalization of problem-solving methods and their assumptions, reverse engineering (of planning systems), library organization for reuse, and types of control knowledge in knowledge-based systems. Part two of the report (this issue) presents the work performed in the period from January 1, 1995 to August 31, 1995. Contents 1 Introduction 4 1.1 Project funding : : : : : : : : : : : : : ...