What is the basic assumption that underlies event-driven modeling?

What is the basic assumption that underlies event-driven modeling?
Answer: Event-driven modeling is based on the assumption that a system has a finite number of states and that events (stimuli) may cause a transition from one state to another. For example, a system controlling a valve may move from a state ‘Valve open’ to a state ‘Valve closed’ when an operator command (the stimulus) is received. Event-driven modeling shows how a system responds to external and internal events.