A Modification of Lee's Path Connection Algorithm

It is shown that a set of diagnostic tests designed for a redundant circuit under the single-fault assumption is not necessarily a valid test set if a fault occurrence is preceded by the occurrence of some ( undetectable) redundant faults. This is an additional reason ( besides economy) for trying to eliminate certain kinds of redundancy from the circuit. However, single-fault analysis may remain valid for some types of redundancy which serve a useful purpose, such as the elimination of logic hazards in two-level circuits.