Advanced information and knowledge processing
The idea behind applying ontologies to information management is that computers could exploit explicit descriptions of the meaning of data on web pages to handle it in a more intelligent way. However, neither the data on the Web, nor the ontologies themselves are permanent and stable. How to effectively use ontologies for computerised information management is still an ongoing research issue. Applying independently developed ontologies together in a dynamic environment where they change over time is even more of a challenge. Research work within the WONDERWEB project focused on designing a component-based framework to cope with distributed ontology evolution. The description of the mechanics of the so-called Semantic Web and the analysis of current practices for change management lead to a number of guidelines for the framework design. Since different tools using the framework should agree on the basic part of the ontology, a meta-model of ontology change specifying a large number of change operations was defined initially. Essentially, the set of basic operations is the 'common language' that tools share for change representation or for augmenting information represented in one formalism with information in another. In order to define standard change operations, the meta-model of two well-known ontology representation formalisms, namely the Open Knowledge Base Connectivity (OKBC) and the Web Ontology Language (OWL) was used. These change operations were precisely defined additions, removals or modifications to the definition of a concept, a property or an ontology as a whole. Finally, the ontology for change operations for OKBC and OWL was extended to a general specification language. The ultimate aim of this specification language is to provide a vocabulary and syntax to express an accurate specification of ontology changes. Moreover, change operations were aggregated into composite operations that perform several modifications in one step. By choosing either composite or simple operations, the level of refinement of a change specification can vary. To provide some evidence of the usability of the framework, parts of it have been implemented in automated tools with the aim of conducting theoretical and practical studies.
