Equivalence and Dominance Relations Between Fault Pairs and Their Use in Fault Pair Collapsing for Fault Diagnosis

Equivalence and dominance relations used earlier in fault diagnosis procedures are defined as relations between faults, similar to the relations used for fault collapsing. Since the basic entity of diagnostic fault simulation and test generation is a fault pair, and not a single fault, we introduce a framework where equivalence and dominance relations are defined for fault pairs. Using equivalence and dominance relations between fault pairs, we describe a fault pair collapsing process, where fault pairs are removed from consideration under diagnostic fault simulation and test generation since they are guaranteed to be distinguished when other fault pairs are distinguished. We demonstrate the full extent of fault pair collapsing by considering circuits with small numbers of inputs. We also describe an efficient fault pair collapsing procedure for larger circuits based on structural analysis