Date: 23 Jul 1980 1640-PDT (Wednesday) From: Mike at UCLA-SECURITY (Michael Urban) Subject: Clarification To: cube-lovers at mit-mc My description of the checkerboard pattern was clearly inadequate, due to haste and the fact that my cube was "borrowed" and scrambled before I had a chance to see precisely what was going on. The pattern in question is formed from Crux Plummeri by applying the "Pons Asinorum" transformation; from the resulting almost-checkerboard, a simple "12-squares" transformation will provide the 6 checkerboards; it isn't hard to inspect the almost-checkerboard to find a trio of center cubies to rotate. The resulting checkerboards are a completely interlocked set. In the following unfolded cube, A/B means that the center and corners are color A, and the edges are color B. A/B C/A B/D D/E F/C E/F I don't THINK anyone has mentioned this pattern; the checkerboard pattern mentioned by Greenberg consists of two cycles of three colors each, something like A/B B/C C/A D/E E/F F/D although I may have the handedness wrong. Mike -------