2707	 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. backtrack depth-first search exhaustive search macros combinatorial computing non-attacking queen s problem difference-preserving codes pentominoes tiling problems squaring the square
