Abstract: Failure diagnosability and correctability of discreteevent systems are widely studied. This paper mainly focus on the question about correcting failure events of discreteevent systems (DESs) under the condition that failure events are diagnosable but uncontrollable, for making the system run within accepted states. With the formalization of correctable states, A correcting model based on state tree is proposed. Meanwhile, the necessity of correctable states is derived and an algorithm for checking correctable states is proposed.

Key words: discreteevent system; faulttolerate system; correctability