On the generation of small dictionaries for fault location

Fault location based on a fault dictionary is considered. To justify the use of a precomputed dictionary in terms of computation time, the computational effort invested in computing a dictionary is lirst analyzed. The number of circuit diagnoses that need to be performed dynamically, without the use of precomputed knowledge, before the overall effort exceeds the effort of computing a dictionary, is studied. Experimental results on ISCAS8.5 circuits show that for relatively small numbers of diagnoses, a precomputed dictionary is more efficient. A method to derive small dictionaries without losing resolution of modeled faults is then proposed. Methods to compact the resulting dictionary further, using compaction techniques generally applied to fault detection, are then described. Experimental results are presented to demonstrate the effectiveness of the methods presented. Internal observation points to increase the resolution of the test set are also considered.