28 Dec
2014
28 Dec
'14
11:09 a.m.
I was thinking in terms of: - using only the seven pieces from one instance of the toy, - distinguishing between pieces which are different colours (so the two Zs are different) - NOT 'identifying' particular faces of pieces (so the 'Zs' can be flipped 180 degrees) - touching faces are identically laid over one another, so there are only a finite number of solutions - NOT distinguishing between two arrangements which can be physically translated to each other The planar constraint (required to light all pieces) only applies if they are all required to light up. The question of the number of arrangements is rather prompted by the 'endless' claim on the packaging. :-) Guy