Message #3646

From: damienturtle@hotmail.co.uk
Subject: Re: Physical 4D puzzle achieved
Date: Sun, 12 Feb 2017 23:46:17 +0000

Melinda,

>In my last message I mentioned that it appears that moving both end caps to opposite sides (as opposed to "ends") works. That looks to be a 90 degree rotation of the central black face, and exchanges red-blue stickers with other colors. Can someone confirm or refute that?

I realised my previous post might not be clear on a few things, so I want to address this explicitly. If I understand correctly (please correct me otherwise), you are taking the two 2x2x1 end caps off, rotating (not twisting) the ‘black cube’ and then replacing the end caps, such that the red and blue stickers mix with other stickers. This rotation of the black face on the physical puzzle seems tempting and I thought it was a valid, normal twist of the 4D puzzle at first glance, but I now realise I was wrong.

However, it does lead to a legal configuration, and corresponds to performing a normal twist of the black face then rotating the 8 corners of that face in a certain way. It can be performed in 9 twists in MC4D, though only 5 if 180 twists could be done in one click, and is equivalent to the 2x2x2 position obtained by performing U2 R2 F2 U2 on a solved cube.

It might not correspond to a normal twist on the 2^4, but it seems like it would lead to an interesting solving experience in its own right.

Also, if the black face is rotated such that the red and blue stickers don’t mix with other stickers, which is the same as rotating the middle 2x2x2 about the long axis, then it is a valid twist, no problems.

I’ve only skimmed through Christopher’s posts on the subject, but I should mention that he seems to have come to the same conclusion independently, which is reassuring.

Matt