Methods for Presenting Ontological Knowledge to the Users • Michal Laclavik 1 , Zoltan Balogh 1 , Nguyen T. Giang 1 , Emil Gatial 1 , Ladislav Hluchy 1 1 Institute of Informatics, Slovak Academy of Sciences, Dubravska cesta 9 845 07 Bratislava, Slovakia laclavik.ui@savba.sk Abstract. In this article we discuss approaches of presenting formalized knowledge. We focus on knowledge represented by ontology. Ontologies are powerful for knowledge representation but are comprehensible for experts mostly, thus they need to be transformed to a human-understandable form. We discuss different alternatives such as trees, graphs or semantic web activities based on markup languages. We also describe our approach used within the scope of the Pellucid project. Our approach is based on OWL ontology, commercial standards and technologies such as XML, RDF, XSLT. The key idea is to transform knowledge in OWL to plain XML, which is then transformed to HTML by XSLT templates 1 Introduction If knowledge is represented by ontology, naturally there are several ways how to present it. It is important in Knowledge Management Systems not only to capture, store or discover knowledge but also to return appropriate knowledge in a human understandable form. 1.1 Object Tree The Object Tree is the base of ontology. A hierarchical object tree with properties is widely and commonly used method, for example in ontology editors such as Protégé[1] or OilEd[2]. However, this approach is mostly understandable to experts, who understand ontology. As an evidence of this fact can serve our experience with developing the so called “browse window (BW)”[3], which was powerful in returning knowledge from KB but was not understandable by end users. As a result we can say that this approach is very valuable for people who understand the structure of knowledge in ontology, they can read it fast and get familiar with it. BW was developed as a part of first Pellucid Prototype[4]. • This work was supported by EC Project Pellucid 5FP RTD IST-2001-34519 and Slovak Scientific Grant VEGA 2/3132/23