Ontologies will play a pivotal r61e in the "Semantic Web", where they will provide a source of precisely defined terms that can be communicated across people and applications. OilEd, is an ontology editor that has an easy to use fi'ame interface, yet at the same time allows users to exploit the full power of an expressive web ontology language (OIL). OilEd uses reasoning to support ontology design, facilitating the development of ontologies that are both more detailed and more accurate.

Ontologies are set to play a key role in the "Semantic Web" by providing a source of shared and precisely defined terms that can be used in descriptions of web resources. Reasoning over such descriptions will be essential if web resources are to be more accessible to automated processes. SHOQ(D) is an expressive description logic equipped with named individuals and concrete datatypes which has almost exactly the same expressive power as the latest web ontology languages (e.g., OIL and DAML). We present sound and complete reasoning services for this logic. 1

the FaCT and iFaCT systems [4]. CORBA was chosen because it is not tied to any particular language or platform. In particular, CORBA can be used with both Lisp and Java running on both Unix and Microsoft platforms. The CORBA solution has all the advantages mentioned above. ffl It facilitates the use of the Lisp implementations by non-Lisp client applications, for example in the TAMBIS (Transparent Access to Multiple Bio1 logical Information Systems) project, where the DL server is used by a Java client [1]. ffl The generic API is defined using CORBA's Interface Definition Language (IDL), which can be mapped to various target languages. ffl The application communicates with the DL via a CORBA Object Request Broker (ORB). The DL server and client application may or may not be running on the same physical machine. ffl It would be possible to substitute FaCT or iFaCT with another DL reasoner, for exam

Most enterprises agree that knowledge is an essential asset for success and survival on a increasingly competitive and global market. This awareness is one of the main reasons for the exponential growth of knowledge management in the past decade. Our approach to knowledge management is based on ontologies, and makes knowledge assets intelligently accessible to people in organizations. Most company-vital knowledge resides in the heads of people, and thus successful knowledge management does not only consider technical aspects, but also social ones. In this paper, we describe an approach to intelligent knowledge management that explicitly takes into account the social issues involved. The proof of concept is given by a large-scale initiative involving knowledge management of a virtual organization.

The use and importance of ontologies is becoming more widespread, however building ontologies is largely a black art. The aim of this paper is to identify and characterise what we currently know and to move towards the longer term goal of developing a comprehensive unified methodology. We first identify dimensions for characterising ontologies, to be used as a basis for noting which techniques and guidelines for building ontologies apply in different circumstances. We then give an overview of the current state of the art, noting that most work addresses just a small part of the life cycle. The very few more complete methods are limited to case studies involving single ontologies and they are hard to compare. In the main part of this paper, we examine two such methods and give a framework for comparing and unifying them. We emphasise that different approaches are required for difference circumstances, and give some guidelines for when to use which techniques. We conclude by ...

Exploiting the full potential of the World Wide Web will require semantic as well as syntactic interoperability. This can best be achieved by providing a further representation and inference layer that builds on existing and proposed web standards. The OIL language extends the RDF schema standard to provide just such a layer. It combines the most attractive features of frame based languages with the expressive power, formal rigour and reasoning services of a very expressive description logic. 1

Increasingly, effort has been devoted to surveying ontology-related research studies from various aspects. However, no survey is available for the ontology library system. For this reason, we decided to examine existing library systems in this paper. First, we identified the main criteria (management, adaptation, and standardization) for evaluating the functionality of the library systems. Then, based on the further enriched criteria, we surveyed most existing ontology library systems. Finally, we summarized the comparison and proposed various important requirements for structuring ontology library systems. The ontology library systems surveyed include: WebOnto, Ontolingua, DAML Ontology Library System, SHOE, Ontology Server, IEEE Standard Upper Ontology, OntoServer and ONIONS. 1.

. Ontologies allow the abstract conceptualisation of domains, but a given domain can be conceptualised through many different ontologies, which can be problematic when ontologies are used to support knowledge sharing. We present a formal account of ontologies that is intended to support knowledge sharing through precise characterisations of relationships such as compatibility and refinement. We take an algebraic approach, in which ontologies are presented as logical theories. This allows us to characterise relations between ontologies as relations between their classes of models. A major result is cocompleteness of specifications, which supports merging of ontologies across shared sub-ontologies. 1 Introduction Over the last decade ontologies --- best characterised as explicit specifications of a conceptualisation of a domain [17] --- have become increasingly important in the design and development of knowledge based systems, and for knowledge representations generally. They...

We describe the ingredients of an intelligent agent (a broker) for configuration and execution of knowledge systems for customer requests. The knowledge systems are configured from reusable problemsolving methods that reside in digital libraries on the Internet. The approach followed amounts to solving two subproblems: (i) the configuration problem which implies that we have to reason about problem-solving components, and (ii) execution of heterogeneous components. We use CORBA as the communication infrastructure.

Ontologies and problem-solving methods are promising candidates for reuse in Knowledge Engineering. Ontologies define domain knowledge at a generic level, while problem-solving methods specify generic reasoning knowledge. Both type of components can be viewed as complementary entities that can be used to configure new knowledge systems from existing, reusable components. In this paper, we give an overview of approaches for ontologies and problem-solving methods. 1 Introduction In 1991, the ARPA Knowledge Sharing Effort [NFF 91] envisioned a new way in which intelligent systems could be built. They proposed the following: "Building knowledgebased systems today usually entails constructing new knowledge bases from scratch. It could be done by assembling reusable components. Systems developers would then only need to worry about creating the specialized knowledge and reasoners new to the specific task of their system. This new system would interoperate with existing systems, us...