On the Necessity to Examine D-Chains in Diagnostic Test Generation—An Example [Letter to the Editor]

In a recent paper by Roth,
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a method called the D-algorithm was developed for generating diagnostic tests for failures in acyclic switching circuits. o Of tnhee innovations of his D-algorithm was that it could follow parallel paths, or “chains” of paths, carrying the “failure” signal to the outputs. This allows him to guarantee finding diagnostic tests for failures in circuits with reconverging fan-out, something none of the old “sensitized path” algorithms could do. However, an example demonstrating the need for examining chains was not presented in the paper. To give such an example is the object of this letter.