ABSTRACT
The family of burr or notched-stick puzzles is a large and prolifi c one, with offspring numbering in the hundreds or even thousands, depending upon how one counts them, and with more being born all the time. This book is not intended to be a compendium of puzzle inventions, past and present. One yardstick for inclusion is the extent to which the underlying idea behind the puzzle is logical and mathematical rather than simply mechanical. Symmetry is an important consideration. In this chapter we will conclude the discussion of square-stick burrs by considering only those having certain kinds of symmetry. This is an appropriate point at which to discuss symmetry.
