To Fergus Duniho: Well, if that is indeed the historic array of Bird, then
a Hamming distance of at least three (as I have specified) would be more
than sufficient. So I would not change that demanded difference of three.
I would like to keep the Hamming distance, because shifting a group of
pieces has an immense effect on the properties of a starting array. And I
think that the so created valid CRC arrays obviously are distinct from
GC.