* ab : RGB ? BRG or (RGB)
* ba : RGB ? GBR or (RBG)
* aba : RGB ? BGR or (RB)

The notation in parentheses is the cycle notation.

Note that the action aa has the effect RGB ? GRB ? RGB, leaving the blocks as they were; so we can write 1=''aa'' = ''e''.Similarly,
* bb = e,
* (aba)(aba) = e, and
* (ab)(ba) = (ba)(ab) = e;so each of the above actions has an inverse.

By inspection, we can also determine associativity and

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