[Help Thread] FMC Discussion

One thing to remember is that the 6-move edge 3-cycle, if you are fortunate enough to find an insertion point for it, has 4 variations which can be thought of as cyclic shift variations (allowing for switching the order of commuting moves) of the alg in face-turn notation.

For example, M U2 M' U2 translated into face turns is L' R B2 L R' U2. But this can be replaced by any of these other 3 algs:

R B2 L R' U2 L'
L' B2 L R' U2 R
B2 L R' U2 L' R

Considering all four algs doubles your opportunity of getting some cancellation, and also increases your chances of multiple cancellations. If you have to do a setup move in order to use a form of the 6-move alg, the opportunities for cancellations are much reduced, of course.

I also decided to determine all the cube positions having unsolved edges, but all corners solved, up to a distance of 7f*. I provide one maneuver for one element of each symmetry class in the spoiler below. Of course, as the number of unsolved edges goes up, the probability of finding an insertion point matching the configuration goes down, so many of these cases are probably not worth learning.

Code:
positions requiring 6 moves
---------------------------
3-cycle
B R2 B' F D2 F'  (6f*)

5-cycle
B F' R' B' F D  (6f*)
U' B D' U R' D  (6f*)
B' D' U R D U'  (6f*)
U' B' D' U R D  (6f*)

pair of 2-cycles
B2 F2 D2 B2 F2 U2  (6f*)
F2 D2 B2 D2 F2 U2  (6f*)

pair of 3-cycles
R D2 U2 L' D2 U2  (6f*)
B2 F2 U' B2 F2 D  (6f*)
U2 L' D2 U2 R D2  (6f*)

six 2-cycles
B2 F2 L2 R2 D2 U2  (6f*)
B2 F2 U2 L2 R2 U2  (6f*)
D2 B2 F2 L2 R2 U2  (6f*)
D2 F2 L2 R2 F2 U2  (6f*)

positions requiring 7 moves
---------------------------
3-cycle
D B' F L2 B F' D  (7f*)

5-cycle
D' U' B' D' U R D2  (7f*)
D' U' B D' U R' D2  (7f*)
D2 U F D U' R' D  (7f*)
D2 U F' D U' R D  (7f*)
D R' D U' B D2 U  (7f*)
D B F' R B' F D2  (7f*)
D' B' D' U R D2 U'  (7f*)
D2 F D U' R' D U  (7f*)
U2 B' D' U R D U  (7f*)
D2 B F' R B' F D  (7f*)

pair of 2-cycles
U' L2 R2 D2 L2 R2 U'  (7f*)
D' R2 D2 R2 D2 R2 D'  (7f*)

pair of 3-cycles
D U2 L D2 U2 R' D  (7f*)
D U2 L' D2 U2 R D  (7f*)
U R' D2 U2 L D2 U  (7f*)
U R D2 U2 L' D2 U  (7f*)
D' B2 F2 U' B2 F2 D2  (7f*)
D2 B2 F2 U B2 F2 D  (7f*)

pair of 3-cycles and pair of 2-cycles
L' R2 B2 F2 R' D2 U2  (7f*)
U' L2 R2 D' B2 F2 D2  (7f*)
B2 F2 D' U2 L2 R2 U'  (7f*)
U2 R' B2 F2 L' R2 D2  (7f*)
U2 L2 R2 U B2 F2 D  (7f*)

six 2-cycles
U' B2 F2 L2 R2 D2 U'  (7f*)
U' R2 B2 F2 R2 D2 U'  (7f*)
U' B2 F2 U2 L2 R2 U'  (7f*)

For 2C,2E positions, I get 10 moves for the minimal alg. The 10f* cases (distinct w.r.t. symmetries of the cube) are:

Code:
F R2 D2 L B L' D2 R F' R  (10f*) 
L' F' L2 D2 R' B' R D2 L' F  (10f*) 
F2 D' F' D F' R2 B U' B' R2  (10f*) 
F2 R2 B' D' B R2 F' U F' U'  (10f*) 
F R' F R F2 U2 B L B' U2  (10f*) 
R B2 L' D L' D' L2 B2 R' U'  (10f*) 
B2 R2 D' R' D R' B2 L U' L'  (10f*) 
F' L2 B D' B' L2 F2 U' F' U  (10f*) 
F R' F' U2 B2 L' B' L B' U2  (10f*)

For pure 2-twist plus pure 2-flip, the minimal alg is 14 moves.
 
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This weeks FMC at mustcube.net was my first "official" FMC attempt, I got a 35 which is great for me, but as with most of my good FMC solutions it feels like a bad skeleton with a lucky finish.
Scramble : F2 D' L2 B D2 F' B2 D2 L F2 D2 F' R' F2 D' R2 U F2 D' R' L' F' D' B' U2 D L' B R2 L'

U R' B U' D' F L' D' L2 R' D R L D' L' F D' F' D F D2 F D F' D' F D2 F' R D' L' D R' D' L' (35)

Premove : L2

2x2x2 : U R' B U' (4)
2x2x3 : D' F L' D' L2 (5, 9)
EO : R' D R L D' L' (6, 15)
F2L-1 : F D' F' D F (5, 20)
Leave 3 Corners : D2 F D F' D' F D2 F' (8, 28)
L3C : R D' L' D R' D' L (7, 35)
Undo Premove : L2 (Cancels)

I looked everywhere for an insertion for the niklas, but I couldn't find anything that cancelled more moves than the 2 that cancelled at the end (AUF + Premove)
 
irontwig - I'm relatively new to fmc, could you explain the third move that cancelled in the niklas? Also, I count 28 moves + 1 premove = 29 with 3 corners left, I don't know how to correctly count premoves so could you give me some insight to how you got 30?
 
The AUF before the niklas cancels two moves.

Leave 3 Corners : D2 F D F' D' F D2 F' (8, 28)

should REALLY be Leave 3 Corners : D2 F D F' D' F D2 F' D' (9, 29) in order to truly leave 3 corners, ignoring premoves. And niklas is an 8 move alg, not a 7 move alg, so the 3cycle you used was really D R D' L' D R' D' L.

So D2 F D F' D' F D2 F' D' D R D' L' D R' D' L L2 (18) cancels into D2 F D F' D' F D2 F' R D' L' D R' D' L' (15)
 
Scramble from CCT: F' U2 B2 U F' D2 U2 L' R D L2 R2 U' F' R' B F' L2 R2 B L' R D2 L2 R'

z2 F R' D L F2 U2 Rw U2 Rw' - 9/9 - X-Cross
U' R U' R' U' y R' U' R - 8/17 - F2L2
y' R' U R - 3/20 - F2L3
U2 R U' R' U R U2 R' - 8/28 - F2L4+OLL (cancelltaion into sune)
y' F2 U R' L F2 R L' U F2 - 9/37 - PLL

Quite lucky, but yeah. PB :D
 
if your FMC PB is with cfop you should practice blockbuilding and comm insertions lol. Surely you could've solved that 3 cycle with an insertion, cancelling some moves.
 
B2 D U B R' D2 B L2 D B2 U2 R F U2 D' F U2 B2 L' D' F' U2 L2 R2 F

Would some of the more experienced FMCers care to show me what they would do with this? It has an extremely lucky 2x2 start.

Premove (R2)

R @ U R' D' : 2x2x2 & 1x2x2 (find premove)
U2 R' U F2 : F2L-1
L' U2 L U' F U' F' U2 : Leave 4 corners

Cool thing, adding an R to the L4C:
L' U2 R L U' F U' F' U2 R' : L3C
R2 : Premove, cancels too!
Insert @ [L2,U'R2U] to cancel 1 move, couldn't find better.

Combine:
R L2 U' R2 U L2 U' R2 (U U) R' D'
U2 R' U F2
L' U2 R L U' F U' F' U2 (R' R2)

R L2 U' R2 U L2 U' R2 U2 R' D' U2 R' U F2 L' U2 R L U' F U' F' U2 R (25)
 
B2 D U B R' D2 B L2 D B2 U2 R F U2 D' F U2 B2 L' D' F' U2 L2 R2 F

Would some of the more experienced FMCers care to show me what they would do with this? It has an extremely lucky 2x2 start.

premove R2
U R' F' R ( find premove R2)
U2 F' U F ( find an additional premove F')

start again with premoves F' R2
Hey this looks nice, screw the previous moves!!!

premoves F' R2
R D' . R 2x2x2 block + 1x2x3 with swapped edges
U R2 place red-blue edge
U' F2 U2 F2 U2 F' U swapping edges leaves 5 corners
F' R2 undo premoves

5 corners left after 14 moves :-)

At . insert B' L B R : B' L' B R' to cancel 2 moves
At : insert U F' U' B' U F U' B to cancel 2 moves

Final solution:
R D' B' L B R U F' U' B' U F U' L' B U R2 U' F2 U2 F2 U2 F' U F' R2 = 26 HTM
Insertions did not really cooperate...
 
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Interesting. This amazes me, but I have no idea where to start.
Just have a look to see if there are other easy blocks to make after the initial one. A pretty common FMC strategy is 2x2x2, extend to 2x2x3, then EO and F2L and then try to force 3 corners left for an insertion. It's basically petrus F2L. You can use the inverse scramble (often known as NISS method) to try and help if you get stuck, and premoves are great too. You'll find loads of info in this thread on that sort of thing. And probably the wiki too
 
Aaaarrgggghhhh....
Just learned something the hard way

When using premoves and ending with X corners left: "solve" the cube without premoves before applying your stickers to go insertion hunting.

I was checking for insertions on nlcuber's scramble, on the 1st cycle I found one with 4 moves cancel, leaving 3 corners at 18 moves.
Then when checking without the premoves I suddenly had some unsolved corners without stickers???

DOH!
 
Aaaarrgggghhhh....
Just learned something the hard way

When using premoves and ending with X corners left: "solve" the cube without premoves before applying your stickers to go insertion hunting.

I was checking for insertions on nlcuber's scramble, on the 1st cycle I found one with 4 moves cancel, leaving 3 corners at 18 moves.
Then when checking without the premoves I suddenly had some unsolved corners without stickers???

DOH!
Well done
 
You can use the inverse scramble (often known as NISS method) to try and help if you get stuck
Using the inverse scramble is a common FMC technique, but using the inverse scramble is not (by itself) what NISS is.
If you carried on the sentence a bit further you'd see that I did mean that switching from normal to inverse in the middle would be NISS. Perhaps I should have put the brackets at the end of the phrase. Sorry for the confusion!
 
Aaaarrgggghhhh....
Just learned something the hard way

When using premoves and ending with X corners left: "solve" the cube without premoves before applying your stickers to go insertion hunting.

I was checking for insertions on nlcuber's scramble, on the 1st cycle I found one with 4 moves cancel, leaving 3 corners at 18 moves.
Then when checking without the premoves I suddenly had some unsolved corners without stickers???

DOH!

You should find that any insertion made within the part of the solution that you have already checked will still work. It will not matter if the premoves are before the scramble, or at the end of your solution, just as long as those moves are still within the sequence. Some (or all) of the unsolved cubies will likely be different colours, however their position within that part of the solution will be the same.

Using your solution for nlcuber's scramble:
Premoves: (F' R2)
Scramble: B2 D U B R' D2 B L2 D B2 U2 R F U2 D' F U2 B2 L' D' F' U2 L2 R2 F
Solution:
R D' . R : 2x2x2 block + 1x2x3 with swapped edges
U R2 : place red-blue edge
U' F2 U2 F2 U2 F' U : swapping edges leaves 5 corners
F' R2 : undo premoves
At . insert B' L B R : B' L' B R' to cancel 2 moves
At : insert U F' U' B' U F U' B to cancel 2 moves

-*-
Premoves before the scramble:
(F' R2)
{Scramble}
R D' (B' L B R (U F' U' B' U F U' B) B' L' B R') R
U R2
U' F2 U2 F2 U2 F' U
alg.garron.us

-*-
Premoves at end of solution
{Scramble}
R D' (B' L B R (U F' U' B' U F U' B) B' L' B R') R
U R2
U' F2 U2 F2 U2 F' U
(F' R2)
alg.garron.us

As you can see, both sequences produce solved cubes.
 
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