GSOS RULES AND A MODULAR TREATMENT OF RECURSIVE DEFINITIONS STEFAN MILIUS , LAWRENCE S. MOSS , AND DANIEL SCHWENCKE c a Lehrstuhl für Theoretische Informatik, Friedrich-Alexander Universität Erlangen-Nürnberg, Germany e-mail address: mail@stefan-milius.eu b Department of Mathematics, Indiana University, Bloomington, IN, USA e-mail address: lsm@cs.indiana.edu c Institute of Transportation System...