Full fault dictionary storage based on labeled tree encoding

The process of fault dictionary compaction can lead to a loss of information that is potentially useful in locating unmodeled failures. The focus of this paper is on developing alternative storage structures that can efficiently represent full fault dictionaries without discarding any information. We present the problem of storing the full fault dictionary storage as a labeled tree encoding problem. Two labeled trees are introduced to represent the diagnostic experiment. For the first tree, the unlabeled tree is stored using a binary string code, while the second tree is constructed so that the unlabeled tree is regular in structure, thus allowing implicit storage. Eight alternative representations based on the three label components are presented, and two existing full fault dictionary representations (the matrix and the list [12] dictionaries) are shown to be special cases in our general framework. Experimental results on the ISCAS 85 and ISCAS 89 circuits are used to study and characterize the performance of the proposed storage structures.