Career
He wrote one book on Model-Based Design and Evaluation of Interactive Applications, and has long been working on user interface modeling languages, and tools for design, development or evaluation of interactive systems In the field of Task analysis he developed the ConcurTaskTrees notation for specifying task models, which has inspired the W3C document on Task Models. He then worked on the TERESA and MARIA eXtensible Markup Language languages for the logical description of multi-device user interfaces.
He has also investigated novel solutions for End-User development in various contexts, and carried out research work for designing and supporting cross-device user interfaces able to dynamically distribute and migrate acress devices.
He has been co-chair of the World Wide Web Consortium (W3C) Group on Model-based User Interfaces. He has been the chair of the International Federation for Information Processing"s Working group 2.7/13.4 group on user interface engineering.