The eight-puzzle exercise has several objectives:

- Analysis of the search space. The eight puzzle is large enough
to be challenging. (A 15-puzzle is sold as a toy; it is too hard to
be used for this exercise.)
- Implementation of basic search algorithms. The algorithms have
much in common; much code can be reused.
- Observation of performance. The various search algorithms have
significantly different performance on this problem.
- Lisp practice. Note that it is easy to write an inefficient implementation that will take large amounts of computer time to solve this problem.