Describing System Functions that Depend on Intermittent and Sequential Behavior

Functional modeling languages have been used to describe processes that react to discrete external events and remain in a constant state until another such event stimulates a change in system state, and are deficient in the area of describing several processes occurring in a specific temporal relationship. The lack of such expressiveness means that it is difficult to apply functional modeling effectively to complex systems where such temporal interactions are key to the correct functioning of the system. This paper presents operators to extend the expressiveness of functional modeling for systems that depend on intermittent behavior or on a strict sequence of events. The effectiveness of these operators is shown for characterizing different orderings of behavior, both in cases where the ordering is precisely specified and where some orderings need not be so specified. Their relevance is shown by considering examples from the domain of automotive systems.