Report Number: CSL-TR-71-15
Institution: Stanford University, Computer Systems Laboratory
Title: Fault equivalence in sequential machines
Author: Boute, Raymond
Author: McCluskey, Edward J.
Date: June 1971
Abstract: This paper is concerned with the relationships among faults as they affect sequential machine behavior. Of particular interest are equivalence and dominancy relations. It is shown that for output faults (i.e., faults that do not affect state behavior), fault equivalence is related to the existence of an automorphism of the state table. For the same class of faults, the relation between dominance and equivalence is considered and some properties are pointed out. Another class of possible faults is also considered, namely, memory faults (i.e., faults in the logic feedback lines). These clearly affect the state behavior of the machine, and their influence on machine properties, such as being strongly connected, is discussed. It is proven that there exist classes of machines for which this property of being strongly connected is destroyed by every possible single fault. Further results on both memory and output faults are also presented.