Generic Fault Characterizations for Table Look-Up Coverage Bounding

Given any combinational, internal fan-out-free network and any complete single fault detection test set (SFDTS) for the network, we consider in this paper the problem of determining the minimal extent to which that SFDTS will cover multiple faults in the network. The basis of our approach is the development of a generic perspective to multiple faults which uses a representation of such faults called an L-expression. This perspective leads to a technique for obtaining the greatest lower bound on the multiple fault coverage capability of an SFDTS by means of a simple table look-up process. In addition to generalizing previously known results regarding multiple fault coverage, two particularly interesting results obtained from this approach are as follows: 1) On the average, every SFDTS for an internal fan-out-free network covers 92 percent of all multiple faults of sizes 8 and less. 2) On the average, every SFDTS for an internal fan-out-free network covers at least 46.1 percent of all multiple faults.