Patrick van Bommel received his master's degree in Computer Science in 1990, and the degree of Ph.D from the Faculty of Mathematics and Computer Science, from the University of Nijmegen, the Netherlands in 1995. He is currently assistant professor at the University of Nijmegen, the Netherlands. He gives courses in information systems analysis and design, and he supervises a semi-commercial student software house. His main research interests include Information Modeling and Information Retrieval. In Information Modeling, he particularly deals with: modeling techniques for information systems, data models for hyperdocuments and web sites, equivalence and mapping of data models, the transformation of (conceptual) data models into implementations and the corresponding transformation of database populations, operations and constraints. In Information Retrieval his main research interests include: document data modeling, WWW based retrieval/filtering and document characterization languages.