[Help Thread] FMC Discussion

[marco.garsed]

That solution is incredible, the F2L-1 is simply ''. You've shown me that 2 twisted corners aren't as bad as I thought.

I definitly quote amazing solve !

 

[cuBerBruce]

20 move FMC

[22:50] <+Kirjava> scramble: R F U2 R2 U L2 D2 L2 F' L' F' B' L2 B2 D F' U2 R F' D2 F2 L' B' D F'
F2L-1: L2 B' F' R F D2
Continue: D L F L' F2 D F D2 L (2 twisted corners left)
So the skeleton is: L2 B' F' R F * . D' L F L' F2 D F D2 L (14)
Insert F' R' F L F' R F L' at * to cancel 6 moves (standard conjugate cancellation)
Insert L' U' L D' L' U L D at . to cancel 4 moves

Solution: L2 B' L F' R F L2 U' L D' L' U L2 F L' F2 D F D2 L (20 moves)

My solution also 20 moves
F2U2BF’L’U’FU’R’F2L2B2L’FB’U2FB’RF2
F2U2BF’L’U’FU’R all corners and 5 edges,
R2F2L2B2L’FB’U2FB’RF2 2 edges swap , L5E.

I note that these 20-move solves are sub-optimal by 5 moves, as the scramble is a somewhat rare 15f*.

Only about 1 in 437 positions are solvable in 15 moves or less.

 

[Attila]

I note that these 20-move solves are sub-optimal by 5 moves, as the scramble is a somewhat rare 15f*.

Only about 1 in 437 positions are solvable in 15 moves or less.

I agree, this was a very easy scramble, i do not want overestimate.

 

[marco.garsed]

I post my PB... I've done it monthes ago with an easy scramble...

Scramble: U' F' D R2 D' U' B' L' D2 U' B' F L' B2 L' D' U2 L' R2 U F2


x-cross: U' B L' F'
extend to double x-cross: U B2 U' R B' .
third couple: U' B U2 B' R'
L3C: U B U B' U' R' U2 R

insert at . canceling 3 moves B U F' U' B' U F U'

full solve: U' B L' F' U B2 U' R U F' U' B' U F U2 B U2 B' R' U B U B' U' R' U2 R

27 HTM...

 

[marco.garsed]

I was trying this scramble...

D B2 D' U R' D L2 U' D2 B2 L B2 L' B F U' B' U' L' U R2 U' B F2 D

I found premove F2...

switch to the inverse

double x-cross: F R' D2 R D' R2 D' F' U2 (9)

I can't go on... after 55 minutes I decided to post just this... -.-''

I think it's a good start...

I often fail at continuations after a nice start... suggestions?

 

[cuBerBruce]

I agree, this was a very easy scramble, i do not want overestimate.

Yes, I figured you knew this was a specially picked easy scramble, and I am not really trying to belittle the fact that you and kinch2002 have found 20-move solutions. My congrats on these good solves.

However, I like to think of number of moves over the optimal solution as another meaningful way of measuring "how good" a solution is. By this way of measuring, there are probably several better solves from WCA and online competitions.

I note that what the Wiki indicates the unofficial record is 19 moves, and that was done by Mirek and Guus on a 18f* scramble. So that solve (both of them arrived at essentially identical solutions) was only one move more than optimal. I think it's highly unlikely there has been a 20-move solution on a 20f* scramble. (20f* positions are so rare, it is unlikely that one has ever occurred in an online or WCA competition.) So one move above optimal seems to be the unofficial record, and I would imagine several 2-, 3-, and 4-moves over optimal solves have been done in online fewest moves competitions (and two in official WCA competitions).

Looking back at Per's FMC web site (back as far as #250), I actually find only one sub one hour solution that is better than optimal+5 (disregarding solves generally thought not to be legitimate). (The 19-move solves were on #203.) That was a 22-move solution on #300, which was an 18f* position. The "classic" format (allowing a whole week) has a few such solutions including three 20-move solutions on 17f* positions (optimal+3) - #309, #348, #356. The two WCA world record solutions were both 22-move solutions on 18f* positions (optimal+4). I haven't checked through the weekly competition results on this site, but I would guess there are some more examples there.

EDIT: Looking back farther in Per's FMC web site, there was a 20-move solution (in half an hour) on an 18f* position in round #235 (optimal+2 sub one hour).

 

[marco.garsed]

F R B' D2 L D' R U' F' U2 L B2 D' F U2 F' R U' B U D' F' B2 R2 B'

x-cross: U B2 L B' (4)
extending to double x-cross: L D L' (3)
F2L-1+EO: R' D R' D R .F D': F' (8)
Leave 5 Corners: D' B' D' B D' (5)

. U F D F' U' F D' F' (8-3 = 5)

: L B' L' F' L B L' F (8-2 = 6)

L5C in 20 moves with two 8 moves insertions that cancel 5 moves... 20+8+8-5 = 31 HTM

full solution

U B2 L B' L D L' R' D R' D R U F D F' U' F D2 L B' L' F' L B L' D' B' D' B D'

31 HTM

 

[Cubenovice]

F R B' D2 L D' R U' F' U2 L B2 D' F U2 F' R U' B U D' F' B2 R2 B'

x-cross: U B2 L B' (4)
extending to double x-cross: L D L' (3)
F2L-1+EO: R' D R' D R .F D': F' (8)
Leave 5 Corners: D' B' D' B D' (5)
. U F D F' U' F D' F' (8-3 = 5)
: L B' L' F' L B L' F (8-2 = 6)
L5C in 20 moves with two 8 moves insertions that cancel 5 moves... 20+8+8-5 = 31 HTM
full solution
U B2 L B' L D L' R' D R' D R U F D F' U' F D2 L B' L' F' L B L' D' B' D' B D'
31 HTM

Very Nice but you missed an opportunity
Your start:
x-cross: U B2 L B' (4)
extending to double x-cross: L . D L' (3)
R' makes a pair
D : F D' F makes F-1
D2 R' B R B' makes EO + pair
B' D2 B D2 leaves 4 corners with 1 twist

at . insert L' U2 L D' L' U2 L D to cancel 3 moves
at : insert D' L U2 L' D L U2 L' to cancel 4 moves

final solution
U B2 L B' U2 L D' L' U2 L D2 R' U2 L' D L U2 L' F D' F D2 R' B R B2 D2 B D2 = 29 HTM

 

[marco.garsed]

Very Nice but you missed an opportunity
Your start:
x-cross: U B2 L B' (4)
extending to double x-cross: L . D L' (3)
R' makes a pair
D : F D' F makes F-1
D2 R' B R B' makes EO + pair
B' D2 B D2 leaves 4 corners with 1 twist

at . insert L' U2 L D' L' U2 L D to cancel 3 moves
at : insert D' L U2 L' D L U2 L' to cancel 4 moves

final solution
U B2 L B' U2 L D' L' U2 L D2 R' U2 L' D L U2 L' F D' F D2 R' B R B2 D2 B D2 = 29 HTM

WTF!?? congrats!

also if my skeleton is 1 move shorter! I didn't see that solution..

 

[Mirek]

I was trying this scramble...

D B2 D' U R' D L2 U' D2 B2 L B2 L' B F U' B' U' L' U R2 U' B F2 D

I found premove F2...

switch to the inverse

double x-cross: F R' D2 R D' R2 D' F' U2 (9)

I can't go on... after 55 minutes I decided to post just this... -.-''

I think it's a good start...

I often fail at continuations after a nice start... suggestions?

It's often easier and faster to find another good start for which continuations are easier.

 

[marco.garsed]

It's often easier and faster to find another good start for which continuations are easier.

thank you... although I wasted time for finding it... but I would waste time in unuseful searching of some good continuations too...

 

[irontwig]

Imo knowing when to give up on a start and try to find another one is a useful but difficult.

 

[Cubenovice]

Imo knowing when to give up on a start and try to find another one is a useful but difficult skill.

Fixed?

I feel the same, it is very difficult to decide when to abandon a specific start.
Especially something like a short 2x2x3...

 

[marco.garsed]

another solve... I don't like it very much but that's what I found in 1 Hour...

anyway 33HTM isn't a bad result for me... it's my "average" if I can say this about FMC XD...

scrambe: R F2 B' L R' U' D' B' F2 L' B D2 L' U F2 U2 D L2 B D' B U2 B D' F2


2X2 block: F2 L2 F L' (4)
extending to triple x-cross: D R D U R D' U' B2 D' F' R2 F [B'] (13-1=12)
orienting two edges: D' B' (3-1=2)
Leave 3 Corners: D2 L' D2 L D'. B D B' D (9)

. D2 B' U' B D2 B' U B (8-2=6)

all but 3 corners in 27 moves so 27+8-2 = 33HTM

full solution

F2 L2 F L' D R D U R D' U' B2 D' F' R2 F D' B' D2 L' D2 L D B' U' B D2 B' U B2 D B' D

any advice?

 

[Cubenovice]

any advice?

For FMC practice I reccommend using scrambles from the weekly comp or fmc.mustcube.net
This allows you to compare your solution to that of several other people.
You may find different starting blocks or (in case of a same start) better continuations.

Edit: when posting solutions for an ongoing competition always use spoiler tags and cleary mention the competition.

 

[tehmaxice]

I got a fairly decent 33 move solution at German nationals, giving me a tie for first place together with Cornelius Dieckmann. Allthough not very technical, and a bit lucky, here it is:

Scramble:
R D2 F' L' U L' D' R U' F U2 R2 U2 L2 B2 L2 U' R2 L2 U2

2x2x3 block: R D' R' L U L D B F D' B2 (11)

F2L, leaving 4 edges: U F' U' F' U2 F' U' F U2 * F2 U' F2 (12)


Insert at * to solve 4 edges: F R F' U2 F2 U2 F2 U2 F' R' F' (11) 1 cancelation


A bit lucky with the two corner edge pairs, and then finding some sequence that solved corners. With the time I had I couldnt find any useful insertion, should maybe have practiced it, since I've never actually done an insertion before.
Well, I'm pretty happy with the result anyway, and if anyone finds an awesome insertion, please let me know!

 

[Cubenovice]

A nice 26 move NISS solution I would like to share:

Scramble R2 B2 D2 F2 D L2 U L2 U F2 L' U F2 D' L' F D' U2 B' L2
Spoiler alert this is the current speedcubers.de forum comp FMC scramble

Spoiler

L' - square
switch to inverse with premove L
R' B2 - pseudo 2x2x2 and 2 pairs
back to normal with premoves B2 R
L' U B - 2x2x2 and 3 pairs
D' L D - 1x2x3
F' L' - pseudo F2L-1 (add extra premove F)
U F' U2 F U' R U' R' U - L3C
F B2 R - undo premoves

L' U B D' L D F'L' . U F' U2 F U' R U' R' U F B2 R - L3C
at . insert B' D B U B' D' B U' to cancel 2 moves

final solution:
L' U B D' L D F'L' B' D B U B' D' B F' U2 F U' R U' R' U F B2 R = 26 HTM

I find than an early NISS check can reveal interesting options, in this case the 3 move pseudo 2x2x2

 

[Tim Reynolds]

A while ago I asked about 4-corner insertions. Thanks to everyone who responded, I got a 9-move 4-corner insertion for NAR

(reposted from MIT Fall)

scramble: D F2 D' L2 D' L' F D2 F2 U' B2 D' R2 D L D2 U R2 (18f)

Spoiler

solution: D' F2 D F2 R L F' R' F L' B R B' R' D2 L' U R D2 L' U' L D L' U L (26f)

inverse scramble: R2 U' D2 L' D' R2 D B2 U F2 D2 F' L D L2 D F2 D'
D R' U' L / D2 R B R' B' / F' R * F R' F2 D' F2 D (17 skeleton)
insert at * R' F L F' R F L' F', 6 moves cancel
insert at beginning L' U' L D' L' U L D, 1 move cancels -> 26

Can anyone find better insertions? I had about 7 minutes left when I found the 17 skeleton, I was about to submit a 31 solution based on
(inverse) D R' U' L / D2 R B R' B' / B' R F2 R' B (13 xxxcross), NISS -> F2 R F2 R' F2 R F2 R' / R F U F' U' R' (24 skeleton)

 

[Brest]

Great solution Tim. I was very impressed!

Here is my DNF (35):

D F2 D' L2 D' L' F D2 F2 U' B2 D' R2 D L D2 U R2

Spoiler

F D2 L' // pseudo 2x2x2
R' U' F U' F2 R' F2 // XXcross
U' R U R' // 3rd pair
U R' U' R // 4th pair
B L U' @ L' B' R' U R U2 // L3C
D // premove fail
alg.garron

Insert @ [U2, B' U2 B] cancels 1 move

F D2 L' R' U' F U' F2 R' F2 U' R U R' U R' U' R B L U B' D2 B U2 B' D2 B L' B' R' U R U2 D (35)

FMC is much harder at an actual competition, away from your own environment.
I was trying to find a better insertion *before* I had fully checked this solution. Then suddenly there was 3 mins left and I rushed it. It would have been 3rd place!
A very good learning experience though.
There is actually a few different places that the premove can be inserted. I'm not sure if this creates any better insertion cancellation possibilities. I did not have the time to look through the whole solution as it was.

My 1st mostly-linear solution was 40. I found the pseudo 2x2x2, so I rescrambled with a premove.

Spoiler

F D2 L' // 2x2x2
R' U' F L' U L // 2x2x3
U' R' U2 R U R // F2L-1
R' F R F' // EO
R U' R' U R U R' // F2L
F U2 F' U' F U' F' // Sune L3C
F R' F L2 F' R F L2 F2 // Aperm
U D' // AUF / premove
alg.garron

I didn't write down the AUF or premove in my notes, as I wanted to look for a better skeleton. Another potential mistake to learn from.

 

[irontwig]

Congrats to the NAR!