This book constitutes the thoroughly refereed joint post-proceedings of the 6th International Conference on Relational Methods in Computer Science, RelMICS 2001 and the 1st Workshop of COST Action 274 TARSKI, Theory and Application of Relational Structures as Knowledge Instruments held in Oisterwijk, The Netherlands, in October 2001.

The 20 revised full papers presented together with an invited paper were carefully reviewed and selected. The papers are organized in topical sections on algebraic and logical foundations of real world relations, mechanization of relational reasoning, and relational scaling and preferences.