Logical Properties of Processes

In this chapter a Hennessy-Milner style modal logic for specifying properties of processes is introduced. These properties express specific capabilities of a process. After the definition of the syntax of this logic and its semantics with respect to processes or labelled transition systems, the power of this logic in distinguishing processes is illustrated by a number of examples, including the vending machines from the previous chapter. It is shown that any property expressed in this logic can be expressed without negation. Next, the logic is related to bisimulation equivalence; specifically, it is shown that no formula of modal depth n can distinguish n-game equivalent processes on that system. Characteristic formulae for processes are explored, as well as an alternative approach to defining the semantics of properties.