I studied mathematics and theoretical physics at the Free University in Amsterdam. After my graduation I got a job at the 'Mathematisch Centrum' in Amsterdam, in the department 'Zuivere Wiskunde' (Pure Mathematics). However, a couple of years ago the institute got renamed and is now called 'Centrum voor Wiskunde en Informatica' (CWI).
In the 1990's, the institute's internal structure was changed in order to transform it into an institute for applicable mathematics. The internal organization (research 'themes', clustered into what has been given the very descriptive name 'clusters') has not much to do with the mathematical disciplines, but reflects the intended applications of mathematics and computer science in the projects which CWI happens to have. In 2002 I was old enough in order that the people responsible for the management of CWI could tell me that my research didn't really fit in the present structure, and they urged me to make place for younger people; which I did --- more or less happily, due to the good financial arrangement. Officially, I did belong to the 'theme' MAS 1, but my main activities were the last few years at the Mathematics Department of the Free University in Amsterdam, where I worked for three days per week. Among others, I gave a course 'Dynamical Systems'. Soon after my retirement my research stopped completely due to a severe illness. But in 2005 I was sufficiently recovered to be able to read and write again, and I started to write an introductory book about discrete dynamical systems. That was finished and published in 2014.Presently I am not doing any serious research, but I read all sorts of interesting mathematics.