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.