Message #3062

From: Melinda Green <>
Subject: Re: [MC4D] Re: Introduction (+ news of my own)
Date: Wed, 28 Jan 2015 17:05:10 -0800

First, more congratulations for David, who Ray points out is our 200th
solver! Roice recently pointed out to me that we got a bump in traffic
recently, and shortly after we got a few first time solvers. I was able
to narrow down the source as Reddit but wasn’t able to find the exact
discussion. David: Is that how you found the puzzle, and if so, can you
reference the discussion?

The fact that he did it without instructions makes the 200 milestone
doubly wonderful. I used all the help I could get, mainly just to get
into the first 100. To Ray’s joke, we actually made partial solves more
difficult when we added random slice masks to the random twists. In the
3^4 case that just means you’ll see some center slice moves. That
doesn’t make the full solve more difficult but definitely makes it
harder to back out small numbers of random twists. A long time ago I
once backed out 8 random twists but those might even have all been 90
degree twists. For reference, here is the wiki page for MC4D solutions
including Mat & Ray’s method that he’s talking about:

Next I’ll just mention that I’ve made some progress toward a physical 4D
twisty puzzle. I plan to post about that for the curious and in the hope
that others might have suggestions for surmounting the remaining
mechanical problems. I wanted to mention the subject here only in
reference to the Happier Cube video which I had not seen, because I had
recently found this one which is similar and I think works better: It too is also extremely
difficult to rotate but seems a little better than the Happier Cube. It
uses telescoping edges instead of squishy foam, which is a design that I
had been thinking of attempting, so I’m glad that someone else tried it,
both because it’s one less project for me, and because the result seems

Regarding your upcoming talk, it’s wonderful that you will be doing
that. My feeling is that no one should need permission to reference
anything that’s been shown or discussed in this public forum. Of course
sufficient attribution is always expected. Please try to record your
talk and post it on YouTube if at all possible. A video on commutators
in general sounds very interesting and useful. And of course we’ll
definitely want it recorded in case anyone’s head actually explodes! :D


On 1/28/2015 12:22 PM, [4D_Cubing] wrote:
> Hi David,
> It has been so long since I last posted here, I took 5 minutes to even
> find it again!
> You mention trying to create a physical 3^4 puzzle, and I wish you
> good luck, I’m sure anyone posting here wants to see that achieved.
> I’ve thought about it a little before, but didn’t get far. This
> closest I know of is simply the skeleton of the tesseract, as seen
> here: The Happier Cube! (Hyper-Cube variation),
> <> maybe it could be used
> as a base for a puzzle? Maybe you have something far more elaborate in
> mind, please let us know if you make any decent progress.
> As it happens, I was going to be posting here anyway. I have been
> asked by fellow speedcube r Simon Crawford to give a talk on some
> mathematics of the cube at Edinburgh University on 18th February as
> part of an "Innovative Learning Week" or something to that effect,
> having given a similar but shorter talk in the past. He recently
> started a postgraduate degree there in some aspect of pure
> mathematics, so his research is poorly understood my myself as my
> postgrad research is in applied mathematics at the University of
> Strathclyde (I’m looking at certain types of networks). There is also
> to be a speedcubing competition, originally planned for the following
> weekend but now postponed to 21-22 March.
> What does that have to do with MC4D? Well, after going through the
> standard talk material of why there are 4.3 x 10^19 states on a 3^3, I
> wish to give a short mention of commutators, and finish by saying that
> the approaches used for analysing the number of states and simple
> commutators can be extended to apply to a wide variety of puzzles. I
> then plan to show off some of the crazier puzzles found around here to
> that effect, perhaps 3^4, 3^7, something from MagicTile, and finishing
> with the mind-bending MHT633, with a 3-cycle commutator having been
> applied to each of them.
> I intend of course to give credit where it is due, depending on which
> puzzles I show off, but I thought I should also state my intentions
> here as way of asking permission and because some may be interested to
> know that I will be showing off these puzzles. I’ve yet to check if
> there is any explicit guidance on using images from the software
> involved, but I will check that too before I proceed.
> If there is interest, I will report back here with any noteworthy
> remarks I might get from my terrified audience!
> Matt
> P.S. While I am unlikely to be doing any solved around here any time
> soon, I still fully intend to return one day and resolve some
> unfinished business I have with these puzzles :)
> ————————————————————————
> Posted by: