As a logician I have worked on the development and formal justification of programming logics. In my thesis (1991) reasoning about dynamically evolving process structures (A proof theory of the parallel object-oriented language POOL) I developed a first sound and complete proof method for a (parallel) object-oriented language, designed and implemented at Philips Research Laboratories. Further development has resulted in a comprehensive proof-theory of a variety of object-oriented features and mechanisms like object creation, aliasing, method calls, multi-threading, inheritance and subtyping. In general I have worked on formal methods. I am a coauthor of the books My other publications can be found at DBLP Bibliography Server and my Google Scholar profile. For my research on programming languages for multi-agent systems I also refer to my publications stored by the Intelligent Systems group at the department of Information and Computing Sciences of Utrecht University). Here you can find some selected publications.