Z-Set and Independent Fault Set based Fault Pair Collapsing for Fault List Reduction

In fault pair collapsing, certain fault pairs are eliminated from the fault list, since those fault pairs are guaranteed to be distinguished by the remaining fault pairs in the fault list. Considering a fault pair is important in the case of diagnostic fault simulation and test generation. The concept of Z-set and independent fault set are used for fault pair formation. Z-set characteristics determine the numbers of fault pairs that are guaranteed to be distinguished by a given fault detection test set. So the remaining fault pairs are considered for further fault pair collapsing process. Independent fault pairs are formed from the collapsed fault list such that each fault in that pair cannot be covered by the tests derived for another fault. For fault pair collapsing process, a fault pair is selected which is not included in the independent fault set. Hence a reduction in the number of fault pairs is obtained. Again to further reduce the numbers of fault pairs, dominance relations between the faults are considered.