Message #3086

From: Melinda Green <>
Subject: Re: [MC4D] Introducing myself
Date: Sat, 21 Mar 2015 20:09:10 -0700

This group is quite varied, including puzzle builders, puzzle solvers,
4D enthusiasts, and pure math types in a number of fields. You are
encouraged to post on any subject even tangentially related to higher
dimensions and/or puzzles.

Here is a link to the results of our first 4D speedsolving contest: We
ran it over Yahoo chat. I’d create a scrambled file and share it with
the group who would solve it and email the result. The winner is the
first correct solution that arrives in my in-box.

I believe it was a no-macro contest? We could try another one allowing
macros, or any other variation people like. I’ll hold a contest whenever
there are 4 or more people ready to compete. So, a quick poll: How many
of you would like to do this again soon, and if so, what dates/times are
good for you and which puzzles and programs do you prefer. I’d like to
keep this to just MC4D solutions but am flexible.

On 3/9/2015 6:42 PM, [4D_Cubing] wrote:
> Melinda,
> I started cubing in 2005 when I was 8, using the keyhole method,
> and I quickly slimmed my times down to a minute or so with that
> method. I was introduced to the real speedsolving community In 2008
> when I went to my first competition, and that was when the 3x3 WR
> was around 9 seconds. Any times less than 14 seconds are still magical
> to me, even though my personal best is 13.5 seconds. I don’t know how
> that happened.
> Anyway, 4D speedsolving sounds like quite a bit of fun =) I’d be
> interested to learn the specifics of competitions. Would they be
> time-based, or turn-based? Macros, or no? Anyway, let me know when we
> may be having one.
> I’ve only given minimum thought to the graph theory of twisty
> puzzles. There’d be incredible symmetry on all the graphs, of course.
> As for Machine Learning, I have absolutely no experience in the field,
> but I love the idea of the field. Does this group work largely on
> furthering knowledge on puzzle theory?
> Thanks,
> -Ryan Echols
> ——– Original Message ——–
> Subject: Re: [MC4D] Introducing myself
> From: "Melinda Green
> <> [4D_Cubing]"
> < <>>
> Date: Sun, March 08, 2015 8:04 pm
> To: <>
> Hello Ryan, and welcome to our group!
> I hadn’t realized that yours was a custom solution. That is very
> impressive! It’s still impressive when people follow Roice’s
> solution, but you earn a special sort of respect when you develop
> your own solution.
> 20 second 3x3 solutions are very fast! Are you old enough to
> remember when the world record was approaching 1 minute? At my
> best I could do it in around 5 minutes, so sub-one minute solves
> are magic to me, and sub-10 second solves are miraculous. We’ve
> done some 4D speedsolving competitions which were quite fun. If
> you get interested in that, we can try to get enough people to do
> more.
> Have you explored any of the graph theoretic aspects of twisty
> puzzles? It seems right up your alley. I’m guessing that you are
> interested in machine learning, is that right? I’m wondering what
> sort of things you most want to work on.
> Happy puzzling!
> -Melinda
> On 3/7/2015 4:58 PM, [4D_Cubing] wrote:
>> Hello everybody!
>> My name is Ryan Echols. I’m 17 years old (turning 18 later
>> this month), and currently a first-year student BYU in Provo,
>> Utah, studying Math. For fun, I like to speedsolve the Rubik’s
>> cube, roller blade, play accordion, do a few card tricks,
>> program, and play Portal 2. My typical time on a standard Rubik’s
>> cube is 20 seconds, and I mention Portal 2 because I was at once
>> a co-world-record holder (the record has long since been broken,
>> but I’m still top 100 in multiple places on the global
>> leaderboards). For work, I’m a research assistant in the Math
>> department with a group that’s currently looking at algorithms to
>> make good Tree Decompositions in Spectral Graph Theory.
>> As for solving the MC4D, I had quite a fun time. I downloaded
>> it early on February 12th, and had bee working on it now and then
>> in my free time for the last 3 weeks until yesterday, March 6th,
>> when I finally finished it. I used no macros, but of course I did
>> use algorithms I knew from the standard Rubik’s cube.
>> So, here comes a long-winded explanation of how I solved it.
>> Don’t feel obligated to read this if you don’t want to. I’ve
>> attached my .log file if you’d like to follow along. anyway, Here
>> we go:
>> My overall approach was similar to F2L (but, more like "first
>> two nested cubes"), with the last cube being solved a bit like
>> Petrus. I started mostly on the red cube, building it in blocks
>> like 2x2x2, then 2x2x3, and 3x3x2, but as I did so, I didn’t only
>> solve the adjacent faces on adjacent cubes, I also solved the
>> next layer out on the adjacent cubes. To solve the last ("upper")
>> layer on the red cube (corresponding to the brown cube), I began
>> thinking about it as starting to solve the brown cube. I built up
>> the brown cube in an F2L fashion, which in turn solved the last
>> layer of the red cube. The particulars of solving F2L of the
>> brown cube were intriguing, though. I’d rotate the totally
>> untouched "middle blue" or "mBlue" cube (opposite red) as to get
>> the desired piece of the brown cube so that it had the brown
>> colored cublet in the over-all brown cube. From that point, I’d
>> one-by-one do 3 or 4 cube turns that each a mounted to a single
>> face turn on the brown cube, as if the brown cube was a typical
>> Rubik’s cube. I did this by rotating one of the cubes adjacent to
>> brown so that the face of brown in question would slide up onto
>> the untouched mBlue cube, then I’d rotate the mBlue cube (with
>> the brown face on it) in the way that would rotate the brown face
>> as desired, then I’d undo the first cube’s turn, putting the
>> brown face back on the brown cube in its new orientation. In
>> certain cases, reversing the turn done to the mBlue cube was
>> necessary also.
>> With the F2L of the brown cube solved, all that was left was
>> the mBlue cube (and the attached adjacent faces of 6 other
>> cubes). At this point, I had to take a step back and think about
>> some theory. Each cube exists in 3 dimensions, of course. our
>> space has 4. In our "flattened-to-3D" representation, let’s
>> suppose our center cube exists in x,y,z. The adjacent cubes
>> sharing the two x,y faces would then exist in x,y,w. The adjacent
>> cubes sharing the two x,z faces would then exist in x,z,w.
>> Likewise, the adjacent cubes sharing the two y,z faces would
>> exist in y,z,w. The totally opposite cube is also in x,y,z. If we
>> only look at the 6 cubes that do exist in z, but ignore z, they
>> make up the faces of just a cube. I call this mindset a
>> "dimension squash". In this case, we squashed z. So, if we
>> dimension squash z, the mBlue cube becomes like the last,
>> unsolved 3rd layer of a normal Rubik’s cube. Of course, any
>> different pieces on the m Blue cube that are in the same x,y
>> spot, but not z, will all act as one as we ignore z. So, I solved
>> the mBlue cube in a Petrus fashion for the start, then just three
>> or four LL algorithms for the last layer, using temporary setup
>> moves and dimension-squashing the various 3 dimensions of the
>> mBlue cube. The specifics of that were the hardest part to figure
>> out.
>> Anyway, thanks for welcoming me to the community!
>> -Ryan Echols