Pathfinder is a knowledge elicitation technique developed in the 1980s. Since that time, Pathfinder has been applied to knowledge elicitation and representation inseveral domains. Some of the many applications include knowledge elicitation of military fighter, Air Battle Managers, Unmanned Aerial Vehicle teams, anesthesiologists, and computer programmers. Pathfinder network is derived from proximities for pairs of entities. Proximities can be obtained from similarities, correlations, distances, conditional probabilities, or any other measure of the relationships among entities.