Relational Methods in Computer Science 6th International Conference, RelMiCS 2001 and 1st Workshop of COST Action 274 TARSKI Oisterwijk, The Netherlands, October 16-21, 2001 Revised Papers - de Swart, Harrie C.M; de Swart, Harrie C.M (Springer Berlin Heidelberg : Imprint: Springer, 2002)