On 5/20/05, Jason Bailey <azrael / demonlords.net> wrote: > Is there an assumption that this is a square or can it be a rectangle? > > ie 4 by 4096 ?? The man said "on a 2**n by 2**n board". This assumption guarantees the board has at least a number of squares (2**(2n)-1) which is multiple of 3 (proof left to the interested reader). Probably it also guarantees that the L-trominos (with 3 squares) can be fitted into the board. The situation is different with rectangles: for example, a 4 by 8 board has 31 squares which are not divisible by 3. So you can't fill it with L-trominos without leaving a blank square. Regards. Adriano.