Dear GAP Forum,

Ed Pegg informed the forum of the Alien Tiles puzzle, which is indeed very
pretty, and does have connections to quite a lot of interesting topics
relevant to GAP, including group theory, linear algebra and algebraic
combinatorics.

Without giving away secrets, some algebra and a few dozen lines of GAP code
enable one to find the shortest move sequence to any position very quickly,
and to answer questions such as the one Ed asks (if I understand his question
correctly). Some interesting questions still remain however, about both the
game as given (7x7, 4 colours) and generalizations to other board sizes,
numbers of colours and different but related sets of rules.

Steve Linton