A Remark on the Nonminimality of Certain Multiple Fault Detection Algorithms

Poage has constructed a complex fault detection algorithm which generates a complete and minimal test set of all multiple stuck-at faults of a given combinational network. Several authors have derived from his method fast and simple multiple fault detection algorithms, which are claimed to generate complete test sets with a "near-minimal" or "near-optimal" number of tests. We show that the algorithms by Bossen and Hong and the algorithm by Yang and Yau may generate test sets with an exponential number of tests (relative to the number of inputs) where a linear number of tests is sufficient for a complete multiple fault detection test set.