# Thread: Big Cube BLD Discussion

1. I did a memo on Chris' scramble since I have a terrible cube, and was sure to DNF even if the cube was good.

Orient: 7s
Centre memo: 3:30
Edge memo: 6:40
Corner memo: 00:30
Total memo = 10:48

My solve time is generally about 20 minutes which I consider pretty hopeless, so I was hoping I could pick up a few tips here. I use pure commutators for centres and edges and do corners like on 3x3. The parity solve is the last thing I do (if applicable). For centres, I get two centres (with successive positions in the cycle) onto the U face, then perform a commutator aqa'q' where q is either U, U' or U2 (depending on the positions of the two centres on the U face). For edges, it is quite similar. I setup two edges (successive edges in the cycle) in positions (preferably on U face) such that I can move 1 to the other's position in just one move (its hard to explain in words). Then I do a commutator with the q move being the move required to do what I just said. For corners, I just use 3OP like I do for 3x3.
I memo using letter object combinations. I just make up stories on the flow and do not have fixed words for fixed letter pairs.
Any comments and suggestions would be greatly appreciated (if anyone understands what I have written ).

2. Wow, Chris, that sounds like a totally cool idea! The only problem I can see with it is that I'm so conditioned now to do the images, I think it would be hard to swap. But I'm going to have to think about it a bit - it seems like it could be so powerful.

3. I tried Chris's scramble. It was kind of a disaster for me time-wise, although I solved it. Memorization did not go well for me at all - it's apparently a bad night for me (bad news because I'm about to do the weekly multi ). (I was also treating this solve as my solve for the Time Machine Competition.) Anyway, here were my breakdowns for Chris's scramble in post #1:

Total memorization time: 5:34.22
Total solving time: 4:54.61
Total overall time: 10:28.83

1) 14.54 orient the cube
2) 1:56.02 memorize centers
3) 2:28.21 memorize edges
4) 33.92 review memorization
5) 21.53 memorize corners and pull on blindfold
6) 28.53 solve corners except parity
7) 1:45.56 solve centers
8) 14.45 fix corner parity
9) 2:26.07 solve edges

Since it was a bad solve for me, it's not necessarily a good measure of my relative times; it seems like these breakdowns are most useful on good solves, not average or bad solves. So it's probably not very useful data.

4. dbeyer: to find the optimal solution I believe that you can set parameters and check on Clement Gallet's wonderful solver. However it only runs on mac/linux

cheers

5. Would anybody be interested in looking up the optimal algorithm for
Urb -> Rbu -> Bur

I've found several nice 10 move solutions.
On a 4x4:
(3L) y [rU2r' u' rU2r' u] y' (3L)'
U x [uR2u' r' uR2u' r] x' U'

For clarificaiton, I am not giving the directional solution but rather the components fully written in SABA'B'S' form
S: U x
A: uR2u'
B: r'

A nice trick to look at for this case, [Urb, Fld, Ldf]

Fld and Ldf are in the same corner orbit around the DFL corner.
So lets view the Urb as the lone cubie.
r' and we have interchangeability with the Urb and Fld on the F plane.
r2 and we have interchangeability with the Urb and the Ldf on the f slice.

So we see our insertion and interchanging points for an A9 cancellation.
Obviously, they are on the F plane and f slice. Now lets make this a finger trick friendly case. Quite simply by doing an x cube rotation. Preserving r turns, and transforming F and f turns into U and u respectively.

x r' U2 r'u'r U2 rur2 x'

Enjoy,
Later,
DB

6. Originally Posted by dbeyer
Would anybody be interested in looking up the optimal algorithm for
Urb -> Rbu -> Bur
I have a truly marvelous demonstration of a 9 mover for this case which this margin is too narrow to contain.

Actually I really did discover a way to do this cycle in 9 turns, but as a side effect it also does a 3 cycle of x-centers around the corner diagonally opposite through the cube.

I'll try to see if the idea I am using for my 9 cycle can be done in a such a way as to avoid the "side effect" cycle on the back of the cube.

Chris

7. I'm not really a BLD cuber, but may I ask Mike and Chris, How do you memorize so fast? I assume it has to do with intelligence, or memo system righ?

8. Originally Posted by V-te
I'm not really a BLD cuber, but may I ask Mike and Chris, How do you memorize so fast? I assume it has to do with intelligence, or memo system righ?
Having a memory system certainly helped me to speed up my memorization quite a bit, but there are people who are truly out of this world fast at memorization using either pure visual (pure rote memory) techniques, or a mix of this and more standard memory techniques.

Part of it also is practice. There is a certain "fudge factor" when memorizing that you have to learn to fight through. For example, when you memorize something and you know that you know it, but you can't recall it. Then you REALLY think hard and finally it comes to you. You get a lot of that, but you have to learn to fight through and recall it faster and faster with each practice solve. BLD is what I practice, I don't really speedsolve much anymore compared to what I used to. Like anything, the more you practice the better you get at it. Now if only I could figure out how Ville and Rafal achieve their level of craziness

If you're interested in journey/image memorization techniques here is a link to what I use.

Chris

9. Originally Posted by cmhardw
Originally Posted by dbeyer
Would anybody be interested in looking up the optimal algorithm for
Urb -> Rbu -> Bur
I have a truly marvelous demonstration of a 9 mover for this case which this margin is too narrow to contain.

Actually I really did discover a way to do this cycle in 9 turns, but as a side effect it also does a 3 cycle of x-centers around the corner diagonally opposite through the cube.

I'll try to see if the idea I am using for my 9 cycle can be done in a such a way as to avoid the "side effect" cycle on the back of the cube.

Chris
That will add some moves to it. Won't be 9 anymore. Anyways is it something this:

y U' r' f r' f' r2 U y'

Anyways I liked dbeyer's version : written in SABA'B'S' form
S: U x
A: uR2u'
B: r'

10. Originally Posted by siva.shanmukh
That will add some moves to it. Won't be 9 anymore. Anyways is it something this:

y U' r' f r' f' r2 U y'
Wow, no your alg is much more efficient at the pseudo-cycle than mine. My pseudo cycle was:
U' r U2 f' U2 r' U2 f U'

Anyways I liked dbeyer's version : written in SABA'B'S' form
S: U x
A: uR2u'
B: r'
Yes but it is a 10 mover :-P Daniel and I were just talking to try and see which strategy would be more fruitful: try to prove there does not exist a 9 mover for this case somehow, or, hopefully, discover something amazing that only takes 9 moves to solve this case!

Chris

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