Acknowledgement

K.L. Man would like to thank Andrea Fedeli, Michele Mercaldi, Menouer Boubekeur and Michel Schellekens for their cooperation and encouragement.

K.L. Man also wishes to thank Jos Baeten, Bert van Beek, MohammadReza Mousavi, Koos Rooda, Ramon Schiffelers, Pieter Cuijpers, Michel Reniers, Kees Middelburg, Uzma Khadim and Muck van Weerdenburg for many stimulating and helpful discussions (focusing on process algebras for distinct systems) in the past few years.