# Message #4085

From: Jay Berkenbilt <ejb@ql.org>

Subject: Re: [MC4D] 2x2x2x2: List of useful algorithms (please add yours)

Date: Mon, 30 Jul 2018 23:06:28 -0400

I think your IY moves are interesting. I figured out the exact effect of

that move also basically by doing a gyro to push the inner face to what I

call "top" and "bottom", but your argument about using IY and other

non-canonical moves is interesting. I had developed a set of moves that was

equivalent to a 180 twist of half a face so that I could use mod 2 = 0

instead of mod 4 = 0, but I decided not to use it. There is definitely an

argument to be made for restricting to a sequence of moves that can be made

into macros rather than things that map directly to twists on the actual 4D

puzzle. I’d never heard of sune and antisune before, but I looked them up.

I had developed my own sequence for rotating a pair of corners. It’s

slightly longer, and it works using my isolate/manipulate/reverse pattern.

I was never a speed solver. My record with 3^3 was 51 seconds by luck, and

in my frequent solving days, I could consistently break 90 seconds.

Now-a-days, it usually takes me closer to 3 minutes, which I can generally

achieve even if I go years between solves.

It’s very interesting how much similarity there is between our approaches,

especially that we both use the mod 4 = 0 of manipulation of the half

puzzle after pushing stickers to the corners. I guess the puzzle sort of

presents a natural solution method.

Great stuff.

On Mon, Jul 30, 2018 at 10:39 PM Jay Berkenbilt <ejb@ql.org> wrote:

> Great, thanks for that explanation. I never learned or used any Rubik’s

> cube notation. I was 11 or 12 when the cube first came out. I first solved

> it from what I think was the first solution book, called "You can do the

> cube," but shortly thereafter, I developed my own solution method, which I

> have applied successfully to every slider puzzle I’ve ever gotten my hands

> on. Of course this was all pre-Internet, so I just lived in my own little

> world. It didn’t even occur to me to look at standard x^3 or speed cubing

> notation. I guess "U" and "D" must be up and down. That’s good – I had

> used L, R, I, and O for left, right, inner, and outer, and then I had used

> "F" for front, "T" for top, "K" for back, and "M" for bottom to avoid the

> ambiguous "B" (bottom/back). I didn’t think of up/down. My notation also

> involved rotating a given face clockwise about a given axis. I guess it’s

> the obvious way to do it if you’ve ever studied any branch of math that

> uses 3D coordinate systems.

>

> I’m planning on watching all the videos you recently posted along with

> other people’s algorithm and solution videos. I’m eager to compare notes. I

> didn’t put much energy into making my algorithms efficient, but I noticed

> when re-viewing my own video that some of my sequences have possibly

> useful/exploitable intermediate states. I tend to do setup moves that may

> be partially canceled by the actual moves.

>

> I’m looking forward to seeing your videos. I’ll reply to the thread in

> which you originally posted them.

>

> –Jay

>

> On Mon, Jul 30, 2018 at 8:16 PM Marc Ringuette ringuette@solarmirror.com

> [4D_Cubing] <4D_Cubing@yahoogroups.com> wrote:

>

>>

>>

>> Hi Jay!

>>

>> I enjoyed your explanation of your gyro rotation by rolling the pieces

>> around.

>> Clearly we think along similar lines; I bet you’ll like my sticker-based

>> physical 2^4 demo.

>> https://youtu.be/a90NLdJQQSw

>>

>> For my most recent video, you can check out my own Monoflip, that I

>> recorded in a spiffy video side-by-side with its clone in MC4D.

>> https://youtu.be/k6ZSu0xOPbQ

>>

>> Those two videos, by the way, appear in my "old" and my "new" Youtube

>> channels, respectively. I recently started keeping puzzle videos in a

>> different place than my personal ones. I should make a playlist or two

>> ASAP, but meanwhile they can be dug out of my channels, or the links found

>> in my archived messages.

>>

>>

>> For notation, I’ll cut and paste this from Michael Gottlieb:

>>

>> Here’s the notation I’ll use for 2^4 moves. I call the eight faces I

>> (in), O (out), and the standard six 3D face names F, R, U, B, L, D. When

>> discussing the virtual 2^4 cube, I’ll label moves as something like "FR",

>> which means rotating the F(ront) face 90 degrees through an axis centered

>> at the R(ight) face, clockwise as if you were looking from the R face. For

>> physical 2^4 turns, I’ll instead use a face name followed by x, y, or z,

>> which follow the speedcubing notation, of rotating the cube 90 degrees

>> clockwise relative to the right, top, or front face respectively. So "Ry"

>> means rotating the R(ight) cube clockwise relative to the top of it. A move

>> followed by 2 (e.g. FR2) means doing it twice, and followed by ‘ (e.g. FR’)

>> means doing it counterclockwise instead of clockwise.

>>

>> He’s describing exactly what I have been doing, but I have only explained

>> it in my videos, not in text.

>>

>> There has been hardly anything written down – my attempt at an algorithm

>> collection this week was the first such attempt – and pretty much

>> everybody has been just winging it, notation wise. So, feel free to just

>> forge blithely ahead and use whatever makes sense to you.

>>

>> Cheers

>> Marc

>>

>>

>>

>>

>> On 7/30/2018 3:34 PM, Jay Berkenbilt ejb@ql.org [4D_Cubing] wrote:

>>

>>

>> I’m rejoining discussions after a long break. Can you point me to some

>> post where you introduce your notation? I can more or less figure it out,

>> but I’m curious to see whether you described it somewhere. I came up with

>> my own notation during my independent work, and it seems very similar to

>> yours. I haven’t posted mine anywhere since I figured I’d wait and see

>> whether a standard notation had been agreed upon by the list first.

>>

>>

>>

>>

>