Self-checking FSM design with observing only FSM outputs

We deal with the problem of a self-checking FSM design with observing only FSM outputs. We suggest a special PLA description of the FSM behavior that is well suited in practice. It is established that a factorized multilevel synthesis method applied to this PLA description and followed by the gate implementation provides observing only FSM outputs. We assume that a set of faults considered does not demand introducing additional FSA input lines. We also propose a mathematical tool that makes possible for any synthesis method applied to this special PLA description to clarify the possibility of observing only FSM outputs.