Relational and Kleene-algebraic methods in computer science : 7th International Seminar on Relational Methods in Computer Science and 2nd International Workshop on Applications of Kleene Algebra, Bad Malente, Germany, May 12-17, 2003 : revised selected papers - Berghammer, Rudolf, 1952-; Möller, Bernhard, 1953-; Struth, Georg (Lecture notes in computer science,, 2004)