Querying and Visualizing the Semantic Web

The amount of unstructured information on the Web has reached a critical level, suggesting the need for the Semantic Web (SW). The SW expresses an initiative to improve the World Wide Web, by adding semantic content to the provided information, thus making the data accessible not only to humans but to machines as well. The fulfilment of this goal requires the contribution of a variety of research areas and tools: reasoning techniques that give the opportunity to agents/machines to act autonomously on the environment of the Web in order to fulfil the users’ needs and tools for assisting the end users in expressing these needs and comprehending the derived results. This paper presents two systems, namely O-DEVICE and VDR-DEVICE, developed by the Intelligent Systems and Knowledge Processing (ISKP) group at the Department of Informatics, Aristotle University of Thessaloniki, Greece. These two systems are designed to function in the SW environment. O-DEVICE is a system for querying and inferencing about ontologies expressed in the OWL Lite sublanguage and VDR-DEVICE is a visual integrated development environment for developing, using and visualizing defeasible logic rule bases on top of RDF ontologies.