The FMC thread

[blah]

So I started FMC 2 weeks ago because of the forum competition, and it's the funnest (note: not funniest) thing in cubing for me by far and nothing comes close (well, maybe big cubes BLD, which I've quit )

But being a noob and all in FMC (only 6 attempts so far), I couldn't find a place on this forum for me to ask questions about FMC. I believe many would agree that too many speedcubing questions are over-asked in this forum, but I've only ever seen a handful of threads about FMC, hence this thread.

I'd love to read and learn from a lot of good and elegant solutions from the pros here.

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I'll start off with a question I hope the experts here can help me with:

Scramble: U2 R F2 D2 B2 D2 F2 L2 R F2 L U2 B U' B' U2 L2 F' L2 B U2 (21f)

Premove + (Scramble)': D' + U2 B' L2 F L2 U2 B U B' U2 L' F2 R' L2 F2 D2 B2 D2 F2 R' U2
2x2x2: R L' D' (3/3)
Triple x-cross: R' U' B D B2 D2 R2 D B R' (10/13) (EO skip)

13 moves at this stage is very good for me, so I don't want to give up this good start. But, now what?

I see a few ways to end this, but none of them are nice:

Permute remaining edges: (cancelled: R) U2 R' U R U' R' (6/18)
OLL: L' U R U' L U R' (7/25)
PLL: B2 L2 B R B' L2 B R' B (9/34)
Undo premove: D' (1/35)

or

(Different) triple x-cross: R' U' B D B2 D' B R' B' R B (11/14) (EO skip)
Permute remaining edges: U' F' U2 F (4/18)
Remaining corners suck

or

(Different) triple x-cross: R' U' B D B2 D' B R' B' R B (11/14) (EO skip)
Finish off F2L: U F' U' F U' F' U F (8/22) (OLL skip)
PLL + AUF: L2 U F' B L2 F B' U L2 U2 (10/32)
Undo premove: D' (1/33)

So, how would YOU end this? I'd like to see how you guys handle this bad ending.

[Tim Reynolds]

Looking back at your first ending, have you tried doing an insertion instead of an A perm? At worst that's 8 moves=34 total, but there's a good chance you'll find an insertion with a cancellation. I'll keep looking a bit more, but that's my first idea.

Here's another ending for the first solution, one more move but it'll give you another place to look for an insertion:
F2L ending: (cancelled R) U2 R' U2 R U2 R'
OLL: (R U2 R2) U' R2 U' R2 U2 R
AUF, then left with 3 corners.

Also you can try for an insertion on the third solution instead of the U perm, but edge insertions usually don't save many moves over U perms.

For the third solution, that's not all that bad--either (URF URB LUB)(URF RDF UBL) or some other combination of 2 3-corner cycles. That's lots of places to look for insertions--probably would end up at about 32 moves.

I'll start looking for some insertions, see if I find anything good.

[soccerking813]

Just a question about FMC. Why can you pretty much use a different scramble than what is given? Like, why are you allowed to use the scramble inverse and premoves and stuff? It seems like that ruins the idea of solving any situation in as few moves as possible.

[blah]

Just a question about FMC. Why can you pretty much use a different scramble than what is given? Like, why are you allowed to use the scramble inverse and premoves and stuff? It seems like that ruins the idea of solving any situation in as few moves as possible.

Hmm. Never thought about it from that "conservative" point of view before I've always thought the guys who came up with the inverse scramble and premove ideas were geniuses, they're just so simple, so elegant.

But anyway, I think you're right about solving the inverse scramble being solving a "different" scramble. But I have to disagree with you about premoves. Of course you can solve the same scramble without using premoves, it just takes a lot of concentration to know which piece is supposed to go where. Why make life harder when you can just use premoves?

[blah]

Looking back at your first ending, have you tried doing an insertion instead of an A perm? At worst that's 8 moves=34 total, but there's a good chance you'll find an insertion with a cancellation. I'll keep looking a bit more, but that's my first idea.

I thought I read somewhere that insertions generally aren't recommended in competitions due to the time constraint? That's why I haven't been taking it seriously at all. I wouldn't know where to start anyway. Do you really go turn by turn to look for an insertion point with cancellations? Isn't that very time consuming?

[Johannes91]

Do you really go turn by turn to look for an insertion point with cancellations? Isn't that very time consuming?

Inserting one commutator takes me just a few minutes or so (or took, I haven't done that in ages). Inserting two optimally takes a bit longer, but at least quickly looking for really nice cancellations is a good idea.

[Tim Reynolds]

It turns out that you can do that A perm in the first solution in 6 moves. What's really nice is that the insertion is before the first move of the solution, so it's the first thing you'll see.

(before first move) U R D' R' U' R D R' (R' cancels R in 2x2x2)

You're allowed to use stickers in competition, so sticker the pieces that you're using for the insertion. Scramble, start doing the solution. Often you'll look at a case and know that there's no 8-move solution, ignore that position and just keep going. It doesn't take all that long, and with practice is very fast. Doing 2 might take longer, yeah, but 1 is pretty quick.

[Swordsman Kirby]

Looking back at your first ending, have you tried doing an insertion instead of an A perm? At worst that's 8 moves=34 total, but there's a good chance you'll find an insertion with a cancellation. I'll keep looking a bit more, but that's my first idea.

I thought I read somewhere that insertions generally aren't recommended in competitions due to the time constraint? That's why I haven't been taking it seriously at all. I wouldn't know where to start anyway. Do you really go turn by turn to look for an insertion point with cancellations? Isn't that very time consuming?

A single insertion takes me two minutes maximum to find. It's really not that hard once you get the hang of it. :P

[fanwuq]

Just a question about FMC. Why can you pretty much use a different scramble than what is given? Like, why are you allowed to use the scramble inverse and premoves and stuff? It seems like that ruins the idea of solving any situation in as few moves as possible.

Inverse scramble: invert your solution to your inverse scramble and you have just solved the given scramble. So I think that's OK for non-linear FMC, but I almost never use inverse scramble anyway; it just takes too much time.

Premoves: I don't think you know what is a premove. It only makes mismatched blocks look easier. That is all. I've used pseudo blocks during linear FMC and it's not that hard. You don't steal any moves since you have to undo it at the end of your solution anyway. I probably will just deal with the the recognition at competition, but when I have a computer; I abuse it on alg.garron.us.

They are clever techniques and you do have to submit the true solution to the scramble given at the end of the day any way.
You might want to look into linear FMC, where you can't undo any moves. Still can use pseudo-blocks, but not premoves for them to look easier.


Blah,
I did not look much into this, but I would have just did Niklas after solving all edges and inserted an A perm. I haven't seriously tried multiple insertions yet, but I do 1 insertion in about 5-10 minutes without the use of post-it stickers. I just write down all the sticker cycles and look at what I wrote down every single move.
For example:
RGY-->
RYB-->
RBW
I write that down go through every move of the solution and keep close attention if any of stickers of a column line up like RGY and RBW or RGY and RYB.

[blah]

Premove + scramble: R2 F2 + L2 D L2 U F2 L2 D B2 D' B2 L2 D' B L B F U2 B' L2 D U2 (21f)

My shortest solution so far, I'm not happy with it yet:

Solution (A)
2x2x3: D F' R' U F' R' B F' (8/8)
Triple x-cross: B F' L D' L' D F L' B' L (8/16)
Orient remaining edges: U' F U' F' (4/20)
Permute remaining edges and 2 corners: U L' U2 L U2 (5/25) (I don't consider this lucky because I did lots of trial and error to get this)
Undo premove: R2 F2 (2/27)
Corner commutator: F' D2 F U F' D2 F U' (7/34)

(Gray = cancelled moves.)

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Other good starts:

Solution (B)
2x2x3: D F2 R' F' U' B L2 (7/7)
Stuck.

Solution (C)
2x2x3: D F' R' U F' R' B F' (8/8)
Solve random blocks: U F U F' L' B L B' L2 U2 (10/18)
Stuck.

Solution (D)
2x2x3: D F' R' U F' R' B F' (8/8)
Solve random blocks: U F U F' L' B L2 B' L U2 (10/18)
Stuck.

Questions:
1. For solutions (C) and (D), is it ever a good thing to have permutation parity at the end? If not, is there a quick fix to this?
2. Am I over-using premoves? Currently I seem to decide to do premoves as soon as I see a pseudo-2x2x2 block.
3. For corner commutator insertions, is a single move cancellation usually good enough? Or should I try harder to look for 2 move cancellations? How often will I get 2 move cancellations, i.e. once in how many solves?
4. For corner commutator insertions, is it generally advisable to insert in the middle of a double turn? I hope you understand what I mean by this, I don't really know how to phrase it properly.
5. Is doing 3 (or more) premoves ever advisable?
6. What do you consider a "good" number of moves for the 2x2x3? I haven't done much FMC yet, but so far I seem to average sub-10, which I think is pretty decent. But I almost always suck after building my 2x2x3