Just a little more dissection of the 22.95 solve, this time LSE.

 I apparently could not wait to do more typing about the 22.95 Minh Thai solve.  Scroll down to the previous post if you're not caught up here.

LSE refers to Last Six Edges. Four of them are in one of the slice layers, and then you have one edge each on the two other layers. Technically, this term didn't exist until the Roux method was proposed, but that's exactly where you find yourself in Minh Thai's method once you have completed three edges each on two opposite sides.

If you look at the last part of the reconstruction from last time, you have this:

u R' E' R E2 R E R' // LSE 
R2 E E' r2 E M2 E' // centers

If you would like to skip ahead to this part of the solve, perform this on a solved cube: 

z’ D2 U2 F' D2 F' U2 F' L2 F' R2 F' R2 F' L' R' U' L' R F D' from standard solved white top/green front. 

So, looking at the moves that are labeled as "LSE", but from the standpoint of Minh's solution guide, I see that breaks down as follows:

u // Aligns upper and lower layers

R' E' R // Puts upper edge in lower target position From Stage III, part 2 (pg 48) "If both (edges) are somewhere in the horizontal middle layer, it will be easy to flip either one of them into the other one's target position."

E2 // puts lower edge in position to be matched with upper Setup move to do Case #2

R E R' // inserts both edges similar to stage III, part 2 case 2.

At this point, all we have is a Dot Case, and there is no edge orientation to do. So, this is a big skip at this point. Perhaps that's why there's the (E - E' ) in the centers because he's excited, or maybe he's just checking to make sure one of the edges in the back isn't flipped first before he fixes the centers. If he had edge orientation to complete, that would have been between 9 and 14 more moves, at least half of which would have been slice moves. Unlike modern cubes, slices can be quite an effort on 80's cubes. So, without that, you get to skip straight to edge permutation, and while it's the worst one, it's not that bad.

So again, we learned that this solve had relatively simple components, a little luck, and was not a  byproduct of a large available algorithm set.

Because Social Media isn't Verbose, and CLL isn't as common in 1982.

 People have complained to me on more than one occasion that I am verbose. As far as I know, this is a completely undesirable trait most of the time. However, I am always found wanting more information and specificity when I ask about things, so I have attempted to learn how to (mostly) politely interrogate people so that I get the sort of answers that I'm looking for.

When I'm the person giving the answers, it's terrible, but mostly because I have given more answer than the other party wanted, and even sometimes to questions that the other party only wanted a meaningless superficial answer to. I have been told on more than one occasion that I talk too much or overexplain, and even once have been told in response that "people aren't going to read my @#$%^$%$$% novel" when I typed out a thorough answer to something.

Every once in a while, I see something that's a tiny bit underexplained, and it bugs me, but I usually have enough sense to not cause problems. What follows is a byproduct of me now fixing something that was a little bit under-explained (or oversimplified, you pick) and I finally bothered to sort it out myself.

So the first Rubik's cube official record was Minh Thai's 22.95. 

 

https://www.youtube.com/watch?v=WJTZhgrbgt8&t=325s

And, thanks to reddit users /u/qqwref and /u/BrestCubing, a lot of important solves have been reconstructed - including this one - and we'll get to that.  Most of the modern solves are done with a method that everyone is more familiar with, what used to be called Fridrich and is now referred to as CFOP. But, Minh's solve is done with his own method, and it's even well documented. ("The Winning Solution", ISBN 0-440-09795-9, 1982.) 

Minh's book was a step ahead of many things that were available at the time because he had individual orientation algorithms for the second set of corners, when nearly every other solution book had some sort of incremental method for orienting the second set of corners. It was one of the first published cube books to explicitly detail and demonstrate the idea that if you had more algorithms at your disposal you could solve faster.  Interestingly enough, there were also a handful of extra algorithms in the examples that started to make me consider the idea that Minh had actually been able to orient and permute second layer corners in a single algorithm.

So, that leads me to the reconstruction. Michael Gottlieb's (qqwref) reconstruction is as follows:

U L2 D' B2 U' R2 B2 F2 D' F2 L2 R2 F R2 D L2 R2 B' L' D' R F' 


x2 y // inspection 
D' R u D R' y' D' R D R' // FL corners + 1 edge 
y D r' E' L // FL center + 2nd edge 
z2 U y l D R' z' R' x z' r' R2 U2 z D R2 D2 // CLL 
R' l' z M D2 M' // FL 3rd edge 
z2 y R z' M z R' // LL 1st edge 
z' r' L' z D R' E R // LL 2nd edge 
U' u' R E' R' // LL 3rd edge 
u R' E' R E2 R E R' // LSE 
R2 E E' r2 E M2 E' // centers

 

This is typical of modern reconstructions. The scramble is shown first, starting from a solved cube with white on top and green on front, moves are shown in standard Singmaster notation, including cube rotations, and double slashes at the end of a line to give a place to put comments.  So, at the end of line four there, it says "CLL". The implication there is that Minh solved both permutation and orientation in a single algorithm. However, that's not the case. Also, it's largely overlooked because it's typically more move-efficient to orient first before permuting. So, here's my marked-up version of the reconstruction. I added notes in one color and comments in another so I could keep track. The Stage/Section references are from Minh's solution guide.

 

U L2 D' B2 U' R2 B2 F2 D' F2 L2 R2 F R2 D L2 R2 B' L' D' R F'

x2 y // inspection  yellow top, red front 

D' R u D R' (y' D') R D R' // FL corners + 1 edge ends with orange corners on top but still yellow top red front 

(y D) r' E' L // FL center + 2nd edge ends with orange on front, red corners need diagonal swap 

 z2 U y l D R' z' R' x z' r' // corners in correct cycle, orange on bottom 

This is equivalent to the permutation algorithm in Stage 2, Section 1, C3, (LFUF’U’L’) with cube rotations and wide moves.  This is permutation only, so I wouldn’t exactly count this as CLL. 

 R2 U2 z D R2 D2 // CLL corners oriented, orange on left  

This is equivalent to the orientation algorithm in Stage 2, Section 2, T7, (R2 F2 R F2 R2) with one cube rotation. 

R' l' z M D2 M' // FL 3rd edge 

z2 y R z' M z R' // LL 1st edge 

z' r' L' z D R' E R // LL 2nd edge 

U' u' R E' R' // LL 3rd edge keyhole piece is at ‘dr’ for the LL edges 

u R' E' R E2 R E R' // LSE 

R2 E E' r2 E M2 E' // centers

Taking another look at this reconstruction solidified two things for me - one, the confirmation that he wasn't doing full CLL, and second, that he rarely performs any sort of F or F' moves despite how often they appear in his solution guide. I had already gotten a sense of that from some other video of him, but it was nice to have the confirmation from a good reconstruction.

So, that's not to say that _nobody_ was doing CLL in the 80's, it just wasn't Minh Thai. Mark Waterman has a well-documented (on the web, at least) corners first solution that has a CLL step.

The next time we take a swing at this, I will have to look at the "LSE" step.