|In my booklet
"Holey 6-Piece Burr!",
I asked the readers if it was
possible to create a 6-piece burr which required a 'fully legal' twist move.
Computer's Choice 5-Hole
design was discovered, I realized a way
to make this happen. On January 16, 1989, running some special programs, the
computer found a design which has 102 different assemblies, none of which
comes apart with linear moves, but one of which comes apart with a fully legal
twist move. Most twist moves in a burr puzzle can only be made because there
is some space ('slop') between the pieces, and/or the pieces have rounded edges
or are made with a material that has some 'give'. 'Fully legal' means that
the puzzle will physically function even if the pieces are made with some
hard material and there is no space between pieces. Two weeks after my
discovery, I received a very similar, non-unique design from Peter Rosler.
This was Edward Hordern's souvenir puzzle at the 10th International Puzzle