Fault identification using a finite state machine model with unreliable partially observed data sequences

The problem of minimum cost identification of a finite state machine (FSM) using a trace of its event history is addressed. The motivation is fault identification in communication systems, although other applications are possible as well. The event history used for the identification is partially observed, i.e., it is known to be a member of a regular language. Any string which belongs in this regular language is a possible trace of the FSM´s event history. Furthermore, the event history is assumed to be corrupted with deletions, additions, and changes of symbols. The FSM to be estimated is related to a known FSM by performing an unknown number of additions and changes of arcs. An identification algorithm based on a fast algorithm that can correct corrupted data strings generated by a known finite state machine is developed. Examples of the method are provided, including one based on the IEEE 802.2 logical link control protocol