Message #4111

Subject: Re: [MC4D] 2x2x2x2: mini-puzzle "twisty stacky 2^3"
Date: Sun, 02 Sep 2018 20:38:33 -0700

I really like this mini-puzzle. At first attempt, it feels like the easiest approach is to not use any re-stacking once you have purple corners. However, when first solving the 2^4, I would avoid disrupting the corner faces once I had them solved. While I still start by solving the corners of the 2^4, I realized that temporarily disrupting them can speed up solving of the other faces quite a bit. So I’ll be on the lookout for ways to make use of the re-stacking in the mini-puzzle even once the corners are purple.

Here is a more precise algorithm for quickly getting the purple onto to corners of the "twisty stacky 2^3":

  1. Use 2^3 methods to put exactly 4 purple on U/D. (If you start with more than 4 purple corners, do any 2 different re-stack moves, and then you will have at least 4 purple off the corners)
  2. Do M S, and you now have exactly 4 purple corners.
  3. Use 2^3 methods to put the other 4 purple on the U face.
  4. Do M U M (or S U S), and you will have all purple corners.

Another approach to steps 1 and 2 would be to arrange it so that the purple on U and the purple on the bottom corners add up to 4, then do M U M. I’m not sure if that is easier or harder than getting exactly 4 on the U/D faces.