On the transparency of automata as discrete-event control specifications

The problem of maximizing the transparency of specification automata for discrete event systems (DES's) is investigated. In a transparent specification automaton, events that are irrelevant to the specification but can occur in the system are `hidden' in self-loops. Different automata of the same specification on a DES can be associated with different sets of such irrelevant events; and any such automaton is said to be the most transparent if it has an irrelevant event set of maximal cardinality. The transparency maximization problem is theoretically formulated and a provably correct solution algorithm is obtained. The most transparent specification automaton essentially shows the precedence ordering among events from a minimal cardinality set that is relevant to the intended requirement, and should help towards resolving the long-standing problem in specification, namely: how do we know that a specification in automata does indeed capture the intended control requirement?