The design of complex systems involves different formalisms for modeling their different parts or aspects. The global model of a system may therefore consist of a coordination of concurrent sub-models that use different paradigms. We develop here a theory for a language used to specify the timed coordination of such heterogeneous subsystems by addressing the following issues:BSD License
- the behavior of the sub-systems is observed only at a series of discrete instants,
- events may occur in different sub-systems at unrelated times, leading to polychronous systems, which do not necessarily have a common base clock,
- coordination between subsystems involves causality, so the occurrence of an event may enforce the occurrence of other events, possibly after a certain duration has elapsed or an event has occurred a given number of times,
- the domain of time (discrete, rational, continuous...) may be different in the subsystems, leading to polytimed systems,
- the time frames of different sub-systems may be related (for instance, time in a GPS satellite and in a GPS receiver on Earth are related although they are not the same).