Contents 1 Introduction 2 2 Some recollections 2 3 Knowledge games 3 appeared in: JFAK. Essays Dedicated to Johan van Benthem on the Occasion of his 50th Birthday (J. Gerbrandy, M. Marx, M. de Rijke and Y. Venema, eds.), Amsterdam University Press, Vossiuspers, Amsterdam, 1999, ISBN 90 5629 104 1 1 1 Introduction Half a century, 50 years, 600 months, 2609 weeks, 18262 days . . . what is in a
... [Show full abstract] number? An occasion to celebrate | call it a milestone, and write a book when the person in question deserves it. This all applies to you, Johan, and here comes my part in it: digging up some memories from the past, and presenting some ideas for the (near) future of our Knowledge Games project with Hans van Ditmarsch. 2 Some recollections We rst met in 1975 at the Seminarium Grondslagen at the University of Amsterdam, you as an assistant professor at the Philosophy department with Martin Lob, I as a graduate