OWL is the most recently developed ontology language from the W3C. OWL is based on RDF (resource description framework), which is accepted as a formal language of meta-data describing any web resources. The key constructs of OWL are classes, individuals, and properties. Classes in OWL are intended to represent concepts in a domain. OWL classes are associated with a set of individuals (or instan...

OWL is a recommended language for publishing and sharing ontologies on the Semantic Web. To manage the ontologies, several OWL data management systems have been proposed. However, the existing systems have limitations of the scalability and the reasoning. In this paper, we propose an OWL data management system, ONTOMS, which stores OWL data into class based relations, performs complete inverseO...

Although OWL is rather expressive, it has a very serious limitation on datatypes; i.e., it does not support customised datatypes. It has been pointed out that many potential users will not adopt OWL unless this limitation is overcome, and the W3C Semantic Web Best Practices and Development Working Group has set up a task force to address this issue. This paper makes the following two contributi...

OntoUML and OWL are ontology languages appropriated to different knowledge representation levels. In order to have better knowledge representation and reasoning capabilities in OWL ontologies, an Ontology Engineering should be used – which corresponds to the transformation of a conceptual model ontology language, such as OntoUML, to a computational ontology language, such as OWL. This paper aim...

The OWL Web Ontology Language is a new formal language for representing ontologies in the Semantic Web. OWL has features from several families of representation languages, including primarily Description Logics and frames. OWL also shares many characteristics with RDF, the W3C base of the Semantic Web. In this paper we discuss how the philosophy and features of OWL can be traced back to these o...

The W3C Web Ontology Language (OWL) provides the needed expressiveness formulation of complex concepts. However, the codification of an ontology is a thought formalization process that sometimes requires extensive knowledge and is often inaccessible laypersons. The G-OWL (for Graphical OWL) syntax has been designed to make easier the knowledge expression (compliant to OWL) in a graphical way. T...

The Semantic Web [2] aims at making web resources more accessible to automated processes by augmenting web pages with descriptions of their content. Ontologies are used to provide precisely specified meanings for these descriptions, and with the Web Ontology Language OWL [1] a standardised ontology building language is available. A notable feature of OWL is that two of the three OWL species (OW...

In this paper, we describe our approach for representing temporal aggregates in OWL-Time, and a systematic way of mapping iCalendar recurrence sets to OWL-Time temporal sequences. We present several examples of natural language expressions for temporal aggregates and how they would be represented in OWL-Time; some examples can be described in both iCalendar and OWL-Time, while others can only b...

Existing approaches for querying OWL DL do either only operate on syntactic constructs without taking into account the semantics of OWL or do only have a restricted access to the T-Box. We present OWL-SAIQL, the novel Schema And Instance Query Language for OWL DL, that is well suited for ontology extraction. We describe its syntax and provide a model-theoretic semantics for OWL-SAIQL. Furthermo...

.............................................................................................................................................. ix Executive Summary ........................................................................................................................... 1 1.0 Introduction ............................................................................................