Technical Report No. 90--04, pages 1-50 pp.. Hamilton, Ontario, Canada: McMaster University, Department of Computer Science and Systems, 1990.
Abstract: The authors propose a novel approach to concurrency theory which can be characterised by two basic principles: there are three major levels of developments, the system, invariant and observation levels, and the direction of the development proceeds from the observation (bottom) level to the system (top) level. This is in contrast with the way the existing two-level models for concurrency are built, the direction of development proceeding from the system level to the behavioural level. The authors claim that the new three-level approach allows for a better classification of invariant properties of concurrent behaviours, and leads to a model in which issues such as priority systems and nets with inhibitor arcs may be properly dealt with.
Keywords: concurrency theory, observation(s), invariant(s), paradigm(s); priority system; inhibitor arc.