Backtrack Programming Techniques The purpose of this paper is twofold. First, a brief exposition of the general backtrack technique and its history is given. Second, it is shown how the use of macros can considerably shorten the computation time in many cases. In particular, this technique has allowed the solution of two previously open combinatorial problems, the computation of new terms in a well-known series, and the substantial reduction in computation time for the solution to another combinatorial problem. CACM November, 1975 Bitner, J. R. Reingold, E. M. backtrack, depth-first search, exhaustive search, macros, combinatorial computing, non-attacking queen's problem, difference-preserving codes, pentominoes, tiling problems, squaring the square 5.30 CA751105 JB January 6, 1978 9:03 AM 1531 4 2707 2707 4 2707 2753 4 2707 1185 5 2707 2707 5 2707 2707 5 2707 2707 5 2707 3053 5 2707 1329 6 2707 1785 6 2707 1973 6 2707 1992 6 2707 2107 6 2707 2109 6 2707 2412 6 2707 2543 6 2707 2673 6 2707 2707 6 2707 2770 6 2707