Message #4081

From: Jay Berkenbilt <ejb@ql.org>
Subject: Re: [MC4D] 2x2x2x2 solution and analysis
Date: Mon, 30 Jul 2018 09:32:53 -0400

Thanks for that introduction. :-) Also thanks for the tip on playlists.
Here’s a playlist
<https://www.youtube.com/playlist?list=PLDZmdyrIRd44Q6En7wf3kugH0Ldn3zOBU> with
my solution and analysis with the videos in proper order.

On Mon, Jul 30, 2018 at 2:00 AM Melinda Green melinda@superliminal.com
[4D_Cubing] <4D_Cubing@yahoogroups.com> wrote:

>
>
> Welcome back Jay!
>
> Unknown to most of the list is the fact that without Jay, perhaps none of
> this would have happened. Don and I had written the first version of MC4D
> some 30 years ago, but were at an impasse. The implementation was a bit of
> a mess, and neither of us wanted to clean it up, nor open-source it in such
> a state. Jay came along and said "I’ll do that", and did the dirty work
> needed to satisfy our requirements and get it to build on Linux. His help
> was a godsend.
>
> Regarding video series, the solution to making them play in order is to
> create a playlist. You can reorder them, add descriptions, and then just
> share the playlist link. I’ve added you to the 2x2x2x2 HOF and linked to
> your scramble, but once you create a playlist I’ll link to that instead.
>
> BTW, Jay’s solution is #10, the first-10 solutions list is full. As with
> MC4D, I’ll have to settle for the first-100.
>
> It’s great to have you back, Jay!
> -Melinda
>
>
>
> On 7/29/2018 6:25 PM, Jay Berkenbilt ejb@ql.org [4D_Cubing] wrote:
>
> Hello all – this is Jay Berkenbilt, one of the longest time members of
> this group, and the second ever solver of mc4d back in October, 1998. I’ve
> been mostly lurking on this list since its formation, popping up every now
> and then. Several weeks ago, I ordered my physical 2x2x2x2 puzzle and then
> sequestered myself to do my own analysis and solution, free of spoilers
> from the list. I have completed this, and I’m now ready to share my work,
> dive in, and join all the discussions. I’m looking forward to contributing
> and learning.
>
> I have created a YouTube channel
> <https://www.youtube.com/channel/UCedJ9DbblmqBq4H_gWzdL6g/videos?flow=grid&view=0&sort=da> with
> my solution videos. You should view these "oldest first". The videos are
> numbered in order and also linked below in order. Clicking "Play All" will
> show you my videos in reverse order. I don’t know how to fix that.
>
> My solution method is as follows:
>
> - Do a full scramble
> - Get all the blue and green stickers off the corners – some will be
> on and some off right after full scramble, and the next stage works better
> if they are all off the corners
> - Get all the blue and green stickers onto the corners starting from
> all of them off the corners
> - Solve the blue slice
> - Solve the green face as much as possible; sometimes there will be a
> single corner out of orientation or a pair out of orientation such that one
> can’t be rotated using regular 3D Rubik’s cube moves
> - Resolve the final corner orientations
>
> It typically takes me about 15 minutes to do a full solve. I tend to do
> things in a fixed order rather than doing much exploitation of things that
> coincidentally happen to be in an ordered state.
>
> I have created a series of 11 videos, each ranging in length from about
> 2:30 to just under 10 minutes, but most are in the 4 to 8 minute range. The
> videos are as follows:
>
>
> - 00: 0:39 personal introduction <https://youtu.be/h8vtOh58PQE>. You
> can skip this unless you’re curious about who I am and what I look like..
> :-)
>
>
> - 01: 5:18 mapping to mc4d <https://youtu.be/0WcvKsUisqs>. This is my
> discussion of how I map this puzzle to the software mc4d puzzle and how I
> label the slices.
> - 02: 9:19 gyro <https://youtu.be/50Cjqwy2oj8>. My "gyroscopic
> rotation" video. Here I present my algorithm for the 4D rotation that moves
> some other slices into the top and bottom positions. I describe in detail
> how to look at this and how and why it works. My sequence is different from
> the one in Melinda’s introductory video and requires only five moves with
> no "cleanup" moves.
> - 03: 4:06 scramble <https://youtu.be/xJ7YEeE0yTs>. This is the full
> scramble I used for the solution. I’m using a previously posted method for
> scrambling, but I describe from first principles why it is valid.
> - 04: 7:59 blue green off corners <https://youtu.be/_b3GWpD6_VA>.
> First solution stage: moving all blue and green stickers off the corners. I
> also introduce a few move patterns I use systematically throughout my
> solution.
> - 05: 6:14 blue green to corners <https://youtu.be/Be8qJ3AbF_A>.
> Second solution stage: move all blue and green stickers back to the
> corners. It turns out in this case to be all but one, which happens
> sometimes.
>
>
> - 06: 5:02 solve blue <https://youtu.be/IMNfgkTBIto>.. Solve the blue
> face starting from all the blue stickers on the outer corners.
>
>
> - 07: 3:53 green except last corners <https://youtu.be/1ru-3RV022Q>.
> Solve green down to one pair of corners out of orientation such that one of
> them can’t be fixed using regular 3D Rubik’s cube operations.
> - 08: 4:08 final solve <https://youtu.be/dTfL_UjMIxc>. The final
> solution, resolving the pair of non-oriented corners (or "disoriented", as
> I say in the video), with a clear explanation of how my method works.
> - 09: 6:00 corner monoflip demo <https://youtu.be/eu14WmUzmnI>. A
> stand-alone video showing my algorithm for fixing the single corner
> monoflip issue. My algorithm is 34 twists, counting twists of a half slice
> (treating one face as a 3D Rubik’s cube) as a single twist and counting the
> gyro as zero. (One could argue that the half twist should count as two
> because how it is justified, but I’m counting it as one here.)
> - 10: 2:30 pair swap demo <https://youtu.be/zscALET96LY>. A
> stand-alone video showing a common sequence I use to swap two pairs of
> corners. I use this various times during the solution (contrary to what I
> say in the video), but this video demonstrates it in an otherwise pristine
> puzzle, making it easier to follow and understand.
>
> Each video has a descrption with slightly more detail. I hope you enjoy
> these. I’m looking forward to feedback and commentary.
>
> –Jay
>
>
>
>