Letter to the Editor—The Shortest-Route Problem

This letter is a supplement to the excellent review of solutions of the shortest-route problem by Pollack and Wiebenson [Pollack, M., W. Wiebenson. 1960. Solutions of the shortest-route problem—A review. Opns. Res. 8 224–230.] in the March–April, 1960 issue of Operations Research. Four additional solutions are presented, two of which are linear programming methods related to Dantzig's tree method [Dantzig, G. B. 1957. Discrete-variable extremum problems. Opns. Res. 5 266–277.] mentioned in the article.