Message #3693

From: Joel Karlsson <>
Subject: Re: [MC4D] Physical 4D puzzle V2
Date: Thu, 27 Apr 2017 19:31:46 +0200

Hi Melinda,

I do not agree with the criticism regarding the white and yellow stickers
touching each other, this could simply be an effect of the different
representations of the puzzle. To really figure out if this indeed is a
representation of a 2x2x2x2 we need to look at the possible moves (twists
and rotations) and figure out the equivalent moves in the MC4D software.
From the MC4D software, it’s easy to understand that the only moves
required are free twists of one of the faces (that is, only twisting the
center face in the standard perspective projection in MC4D) and 4D
rotations swapping which face is in the center (ctrl-clicking in MC4D). The
first is possible in your physical puzzle by rotating the white and yellow
subcubes (from here on I use subcube to refer to the two halves of the
puzzle and the colours of the subcubes to refer to the "outer colours").
The second is possible if it’s possible to reach a solved state with any
two colours on the subcubes that still allow you to perform the previously
mentioned twists. This seems to be the case from your demonstration and is
indeed true if the magnets allow the simple twists regardless of the
colours of the subcubes. Thus, it is possible to let your puzzle be a
representation of a 2x2x2x2, however, it might require that some moves that
the magnets allow aren’t used.

Best regards,

2017-04-27 3:09 GMT+02:00 Melinda Green
[4D_Cubing] <>:

> Dear Cubists,
> I’ve finished version 2 of my physical puzzle and uploaded a video of it
> here:
> Again, please don’t share these videos outside this group as their purpose
> is just to get your feedback. I’ll eventually replace them with a public
> video.
> Here is an extra math puzzle that I bet you folks can answer: How many
> families of states does this puzzle have? In other words, if disassembled
> and reassembled in any random configuration the magnets allow, what are the
> odds that it can be solved? This has practical implications if all such
> configurations are solvable because it would provide a very easy way to
> fully scramble the puzzle.
> And finally, a bit of fun: A relatively new friend of mine and new list
> member, Marc Ringuette, got excited enough to make his own version. He
> built it from EPP foam and colored tape, and used honey instead of magnets
> to hold it together. Check it out here:
> dessert_cube.jpg I don’t know how practical a solution this is but it
> sure looks delicious! Welcome Marc!
> -Melinda