[Help Thread] FMC Discussion

[Stini]

I think there was a discussion about that somewhere previously and, as far as I can remember, the general consensus was that it's ok as long as you can explain the reasoning behind the move(s). Here it's simply solving a pseudo pair, which leads to an easy 2x2x3. In Finnish competition we actually used to interpret the rule strictly like that and once we had a scramble which had an easy 3-move 2x2x2 but we couldn't use that because the first move would have cancelled the last move of the scramble (unless you did something tricky like leave three corners and make the insertion in the beginning of the solution haha). There are many problems with such a strict approach, for example if you use the inverse scramble, you can't know beforehand what the last move of your solution will be (= first move of the inverted solution). Here I also used the inverse scramble, so the last move of the solution wasn't sure beforehand. For example I could have got a pseudo block, which would have required another pre-move so the starting move of the solution would have been different. As a matter of fact I got a pseudo block here, but the corresponding pre-move happened to be on the B-face. Also I could have cancelled my F pre-move and get a different first move.

 

[okayama]

@Teemu:
I was profoundly moved by your beautiful solution, Teemu. In your start, L B2 R2 U R D, the 5th move R might be a great inserted move. I checked your solution and found your insertion is optimal. Congratulations!

@irontwig:

Isn't that pre-move "related to the scramble" though? Not that I personally think that your solution should have been disqualified, but that's still pretty much what the regulations state.

You mean the following regulation, right?

E2e) The solution of the competitor must not be in any way related to the scrambling algorithm. Penalty: disqualification of the solve.

I'm not sure that scrambling algorithm == scramble, but if so, the statement has room for improvement. Here are some of my opinions:

1. For any solution
Strictly speaking, all, any solution should be related to the given scramble because it solves the scramble.

2. Solution with premoves
If a normal solution (any technique isn't used in it) is approved by the regulation, a solution with a premove should be approved, too.
(proof)
a) Advanced, trained FMC players can recognize a pseudo block without a premove actually, so it is equal to a normal solution. Teemu's solution above is a good example. "B F" should be treated as premoves but "B" is skipped in his explanation. Another good example is Guus' linear solution in FMC #329/speed. He solved it without the premove "D".
b) If a solution with one-move premove is approved, then a solution with any-moves premove should be approved by the inductive method.

EDIT:
Non-premove means that "I will go (from the given state) to the solved state".
Premove X means that "I will go to the state that can reach the solved state by moving X". In other words, "I regard such a state (reaches the solved state by moving X) as the final goal".
Premoves X Y means that "I will go to the state that can reach the solved state by moving X Y".
Premoves X Y Z means that "I will go to the state that can reach the solved state by moving X Y Z".
The difference between these solutions is just a viewpoint/thinking, and there is no cheat.

And conversely, any normal solution, say "a b c d e", can be regarded as a solution "a b c d" with a premove "e", or "a b c" with premoves "d e", or like that. So if premove-used-solution is disqualified, any normal solution should also be disqualified.

3. (Additional) Solution for a inverse scramble
If a solution with any-moves premove is approved, then a solution for a inverse scramble should be approved.
(proof)
a) Just treat it as a solution with premoves (and no-move to solve) for a regular scramble.

4. (Additional) Solution with NISS
(proof)
Clear from the proofs above.

Aside from this logic, these techniques should not be treated as a cheat but as an elegant way to solve this puzzle, Rubik's cube. From a mathematical point of view, these techniques just rewrite a given problem to an equivalent, but easily recognizable problem. If the regulation does not permit these techniques, the regulation should be improved, I think.

 

[qqwref]

As I see it the regulation is only for the most obvious cases where your solution is basically some modification of the inverse scrambling algorithm itself. The whole idea is to prevent people from doing this, as a 20 move scramble will give you a very nice result even if you lose 5 or 10 moves - the regulation is not in place to prevent people from using certain solutions. I don't think a solution with one or two (even three) moves in a row similar to the scramble counts for this. Besides, a really related scramble would be hard to explain anyway.

 

[okayama]

As I see it the regulation is only for the most obvious cases where your solution is basically some modification of the inverse scrambling algorithm itself. The whole idea is to prevent people from doing this, as a 20 move scramble will give you a very nice result even if you lose 5 or 10 moves - the regulation is not in place to prevent people from using certain solutions. I don't think a solution with one or two (even three) moves in a row similar to the scramble counts for this. Besides, a really related scramble would be hard to explain anyway.

Like this, right?

Scramble: D2 L2 F D2 U2 B R2 U2 F' U2 R' D R U2 L' U' R2 F' L2 U F
Solution: R B' R' B' U2 B F' L2 R B R' U' L2 F R2 U L R' D' R F U2 R2 B' U2 D2 L2 D2 R2 B R2 (31 HTM)

2x2x1 block: F' U' L2
More pairs: F R2 U L
Orient edges: R' D' R
2x2x1 block: F
2x2x2 block: U2 R2 B' U2
Pseudo 2x2x3 block: D2
All but 3 corners/edges: L2 D2 R2 B R2

Insert at the beginning: R B' R' * F' R B R' F
Insert at *: B' U2 B F' L2 F

I made this solution by modifying the inverse scramble (of course a cheat), but a judge may not realize it. :rolleyes:

 

[qqwref]

Yes, perhaps they won't see it. Maybe all competitors should have to submit their explanations too, just in case.

 

[Rune]

Yes, the edges sucked, that's why I did not find a good end. I must work on a few standard ways to avoid situations like that.

Nice work Mr Stålgren =)

You should have come to SOC, you are a potentional winner in FMC. (Next time will probably be the Cube day in "Blackan", be there!)

I have guessed on Järnkvist.

 

[guusrs]

Here's my yet another sub-30 solve from Estonian Open:

Scramble: D2 L2 F D2 U2 B R2 U2 F' U2 R' D R U2 L' U' R2 F' L2 U F
(Inverse scramble: F' U' L2 F R2 U L U2 R' D' R U2 F U2 R2 B' U2 D2 F' L2 D2)

Solution: F' B2 R2 B U R U' R2 B2 R' B2 R2 B R' D' L2 D R D' L2 R' U' R2 B2 L' (25 HTM)

Pre-move for the inverse scramble: F

2x2x3: L B2 R2 U R D.
Pseudo F2L minus slot: B' R2 B2 R B2
Leave 3 corners: R2 U R' U' B' R2 B2

Insert D' L2 D R' D' L2 D R at the dot to cancel 2 moves.

I didn't have much time in the end so I was rushing a bit and I felt quite nervous so it's possible that I overlooked a better insertion. I spent quite a lot of time for the start, which caused the time trouble. I was quite surprised to find such a nice start on a scramble with no pairs.

My next try will be in the European championships, I feel anxious already.

Nice ending! I got 27 moves on this scramble with a slightly different start

Gus

 

[irontwig]

Yay, I beat Guus! http://fmc.mustcube.net/results.php?round=312&format=official&metric=htm
Scramble: B' U B2 R2 D B2 L2 U2 D2 R2 D' L2 F2 B2 L U D' F L2 U D2 L2 U' F2 L' D' R2 F' B U
Solution: D2 B2 F' L F' U R L2 B' L U2 B2 F R2 F' U2 L2 F' D2 F L2 D' B U B' D B U2 D R

D2 B2 [2x2x1a]
F' [2x2x1b]
L F' L' R [2x2x3]
R' L U R L2 B' L [EO]
U2 B2 U2 [F2L]
U2 F R2 F' U2 L2 F' D2 F L2 [LLEF (T-perm)]
D' B U B' D B U' [L3C (Niklas)]
U' D R [Pre-moves]

Last two pre-moves were found with a mediocre 2x2x3 beginning.

 

[irontwig]

Yay, I beat Guus! http://fmc.mustcube.net/results.php?round=312&format=official&metric=htm
Scramble: B' U B2 R2 D B2 L2 U2 D2 R2 D' L2 F2 B2 L U D' F L2 U D2 L2 U' F2 L' D' R2 F' B U
Solution: D2 B2 F' L F' U R L2 B' L U2 B2 F R2 F' U2 L2 F' D2 F L2 D' B U B' D B U2 D R (30)

D2 B2 [2x2x1a]
F' [2x2x1b]
L F' L' R [2x2x3]
R' L U R L2 B' L [EO]
U2 B2 U2 [F2L]
U2 F R2 F' U2 L2 F' D2 F L2 [LLEF (T-perm)]
D' B U B' D B U' [L3C (Niklas)]
U' D R [Pre-moves]

Last two pre-moves were found with a mediocre 2x2x3 beginning.

 

[palash_du]

Yay, I beat Guus! http://fmc.mustcube.net/results.php?round=312&format=official&metric=htm
Scramble: B' U B2 R2 D B2 L2 U2 D2 R2 D' L2 F2 B2 L U D' F L2 U D2 L2 U' F2 L' D' R2 F' B U
Solution: D2 B2 F' L F' U R L2 B' L U2 B2 F R2 F' U2 L2 F' D2 F L2 D' B U B' D B U2 D R (30)

D2 B2 [2x2x1a]
F' [2x2x1b]
L F' L' R [2x2x3]
R' L U R L2 B' L [EO]
U2 B2 U2 [F2L]
U2 F R2 F' U2 L2 F' D2 F L2 [LLEF (T-perm)]
D' B U B' D B U' [L3C (Niklas)]
U' D R [Pre-moves]

Last two pre-moves were found with a mediocre 2x2x3 beginning.

yeah and Okayama and me also.
Can you describe your premoves in a bit detail?

 

[guusrs]

Yay, I beat Guus! http://fmc.mustcube.net/results.php?round=312&format=official&metric=htm
Scramble: B' U B2 R2 D B2 L2 U2 D2 R2 D' L2 F2 B2 L U D' F L2 U D2 L2 U' F2 L' D' R2 F' B U
Solution: D2 B2 F' L F' U R L2 B' L U2 B2 F R2 F' U2 L2 F' D2 F L2 D' B U B' D B U2 D R

D2 B2 [2x2x1a]
F' [2x2x1b]
L F' L' R [2x2x3]
R' L U R L2 B' L [EO]
U2 B2 U2 [F2L]
U2 F R2 F' U2 L2 F' D2 F L2 [LLEF (T-perm)]
D' B U B' D B U' [L3C (Niklas)]
U' D R [Pre-moves]

Last two pre-moves were found with a mediocre 2x2x3 beginning.

So why don't you participate in real comp?

 

[irontwig]

yeah and Okayama and me also.
Can you describe your premoves in a bit detail?

Pseudo-blocks with pre-moves D R:
L' B U F' R [2x2x2]
D F' D F D [2x2x3]
But then I find better stuff with the same pre-moves+U' when finishing F2L.

So why don't you participate in real comp?

I wish I could have come to Swedish Open, but I had some stuff I had to take care of. I'll try to get to Swedish Cubeday.

 

[FMC]

hello,
im new to FMC,Im interested in learning two-gen method,
please explain the main ideas or give me some links from which i can learn.
[charles tsai's site:http://www.geocities.com/c_w_tsai/cube/
is not working ]
thanks in advance

 

[RCTACameron]

hello,
im new to FMC,Im interested in learning two-gen method,
please explain the main ideas or give me some links from which i can learn.
[charles tsai's site:http://www.geocities.com/c_w_tsai/cube/
is not working ]
thanks in advance

For FMC, probably start off with blockbuilding - 2x2x2 block, make that into a 2x2x3 block, finish F2L and do LL normally. I'm new to FMC, and that's how I do it. Not sure about the 2-gen method, though...

 

[FMC]

For FMC, probably start off with blockbuilding - 2x2x2 block, make that into a 2x2x3 block, finish F2L and do LL normally

I know these basic ideas,i want to learn something more!

 

[PalashD]

Can someone explain th domino method. I know that first the cube is set into a subgroup then solved but how does it really work?

 

[RCTACameron]

I know these basic ideas,i want to learn something more!

From what I've seen, you could learn stuff like triple x-cross and NISS (whatever that is.) Also, you could do stuff like forced OLL skips.

 

[FMC]

From what I've seen, you could learn stuff like triple x-cross and NISS (whatever that is.) Also, you could do stuff like forced OLL skips.

i know these ideas as well,i have gone through the threads on FMC(completely!)
i often get solves between 35-40 moves,may be i must practice more to get decent
solves.but i desperately need two gen method(this is not just for FMC)

 

[Tim Major]

Try to stay away from OLL and PLL as these generally aren't very efficient. Try to reduce to 3 corners, then find an insertion earlier in the solve, while trying to find one that will cancel.
http://speedcubing.com/chris/bhcorners.html
May help.
If you want any examples, look at some sub 30 solutions. Most use insertions
NISS is solving until you get stuck, then using the inverse of those solving moves, as premoves to the inverse scramble. You can switch to and fro whenever you get stuck, though it's a little time consuming, and will not always help.
Have a look here http://www.speedsolving.com/forum/s...s-and-Techniques&p=15792&viewfull=1#post15792
AvG goes into more detail, and explains simpler. I'm getting off now, so I had no time to really get into explaining full techniques, but I would usually try to block build F2L -1 pair, then reduce it to 3 corners or edges, then use an insertion.
Hope this helps

 

[RCTACameron]

Try to stay away from OLL and PLL as these generally aren't very efficient.

When I do FMC, I will try... but I love them so much!