
- Comparative semantics of a backtrackable rendez-vous, INRIA, Paris France, 24 June 1991
- DLP A language for distributed logic programming, Benelog 91, Universiteit Namen, Belgie, 2 september 1991
- Comparative semantics of a backtrackable rendez-vous, CSN 91, Utrecht, 1991
- Responsibilities in OOP, Seminar COOP 92 -- Computing and Object Oriented Programming, Universiteit van Amsterdam -- Science Data Systems, Sun Microsystems Nederland, 15 jan. 1992
- Asynchronous rendez-vous in distributed logic programming (met E. de Vink) REX Summerschool - Semantics: Foundations and Applications, De Wipselberg (Apeldoorn), 1-4 juni 1992
- Meta-programming in DLP, ECOOP -- Workshop on Reflection and meta-architectures, Jaarbeurs centrum Utrecht, 30 juni 1992
- Distributed Logic Programming for Artificial Intelligence, First Compulog-network workshop on programming languages in computational logic Univerista di Pisa, Italy, 6-7 april 1992
- An object oriented approach to distributed problem solving, RSG.1 Workshop on distributed object oriented computing, Valcartier, Canada, 12-15 mei 1992 (invited)
- An object oriented approach to distributed problem solving, ES92 -- 12'th Annual Conference on Expert Systems of the British Computer Society Churchill College, UK, 15-17 december 1992
- Deja-Vu: A distributed hypermedia framework Multimedia -- Culture, Technology, Interpretation, Trinity College, Dublin, 25-26 maart, 1993
- DejaVu -- Hypermedia in Cyberspace World Wide Video Festival - deconstructing visual formats, World Wide Video Center, The Hague, 14 april 1994
- Integrating WWW and Applications (met M. v. Doorn), Int. Workshop on WWW Design Issues '94, CWI, Amsterdam, ERCIM World Wide Web Working Group (W4G), Amsterdam, Nov 29- Dec. 1
- Music in Time-based Hypermedia (met J.R. van Ossenbruggen), European Conference on Hypermedia Technology 1994 (ECHT'94), The Association for Computing Machinery, Edinburgh, United Kingdom, 18-23 september 1994
- Information management, SGML and active documents (met M. van Doorn), Int. Workshop on WWW Authoring and integration tools, Inria, Rocquencourt, Parijs / Frankrijk, febr. 8-10, 1995
- Integrating applications and the World-Wide Web (met M. van Doorn), Third Int. World-Wide Web Conference, Univ. Darmstadt, Duitsland,
- DejaVU -- a component-based approach to hypermedia, SIKS - geavanceerde informatiesystemen, TUE, Eindhoven, 6 juni 1995
- Bringing Music to the Web (met J. van Ossenbruggen), Fourth Int. World-Wide Web Conference, MIT, Boston, USA, 11-14 dec
- Beyond object-orientation?, SIKS Themadag, Leiden Universiteit, najaar 1996
- Jamming (on) the Web, The 6th International World Wide Web Conference,Stanford University Santa Clara, USA, 9 april 1997
- Web Agent Support Program, Workshop: Logic Programming and the Web - 6th Int WWW Conference,Stanford University,Santa Clara, USA, 7 april 1997
- Hypermedia support for software engineering, Workshop: Hypertext functionaility and the WWW, at the 7th WWW Conference, Brisbane University, Brisbane, Australie, 14 april 1998
- Web Agent Support Program, NWO/DISH Symposium, Vrije Universiteit, Amsterdam, 4 juni 1998
- If Java is the Answer, Object+ Exchange Meeting, Object+ Soestduinen 14 oct 1998
- If research is the question, TTT Database Research Group, CWI, Amsterdam, 8 oct 1998
- Challenges in OO IPA Fall Days, 9 November 1999
- Patterns in Software Architecture, HKU, april 2000
- Gaming is a Waste of Time, Brain Storm, march 2007
- addiction in/to Second Life Utrechte Studenten Vereniging, may 2007
- elements of a chinese language game, at PICNIC 07 september 2007