D-algorithm
Beginner
An early method for working out a test pattern that makes a flaw show up.
Novice
The first systematic method for finding a test for a stuck-at fault, published by J. Paul Roth in 1966. It tracks the good and the faulty circuit at once using a symbol D, pushes the fault’s effect toward an output, and works backward to find the inputs needed.
Expert
Five values (), where means good 1 / faulty 0. It searches over values on internal lines using the D-frontier and the lines still to justify, with implication and backtracking. Complete, but slow on circuits where signals split and rejoin, which PODEM and FAN addressed.