Need help with insertions

[Paiev]

I need some help with insertions for FMC. I understand the concept behind insertions, but I have issues actually finding them. Could someone explain how they go about finding insertions?

For example, take the FMC scramble for the weekly contest:

U2 R' U2 L2 R' F2 R2 U' R' D L2 R2 F L' D' L R2 F2 R2

And here is my solution:

2x2x2: R U' L U2 L U L2 [7]
Triple x-cross: R' D2 R' D R2 B' D L' F' L B F2 [19]
Last F2L Pair: R' D' R D' R' D R [26]

This leaves three incorrect corners. Can someone provide a guide/example for how they would go about finding an insertion for the above solution?

Thanks

 

[pjk]

Moved to Speedcubing forum.

 

[Mike Hughey]

Despite the fact that I'm not very good, I couldn't resist trying.

When I do this, I just put stickers on the remaining corners (for yours, Dfl, Bdr, and Fdr) at the end, and then solve the cube and rescramble. Then I start going through my solve one move at a time, looking for 8-move commutators.

With your solution, the first thing I find is after the sixth move on the 2x2x2. There you have Bur and Bdl interchangeable by turning B2, and Ufr in position, so the commutator [L' F2 L, B2] will do the job. As bad as I am, there's a good chance that's all I'd find. But I'd be disappointed with that - there are no cancellations; surely we can do better than that.

So keeping on going, I also see 2 moves before the triple x-cross there's an A-perm: L D' L U2 L' D L U2 L2, which cancels a move, but is unfortunately 9 moves long, so it still comes out to 8 moves - no better.

Unfortunately, I don't see anything else. But I'm bad at this. I'm looking forward to seeing how someone who's good would find better.

 

[Paiev]

Thanks Mike. That trick with the stickers is incredibly helpful (incidentally, I'm using Post-It notes instead of stickers; is this allowed in competition?), and I found an 8-move insertion for the example solve. I'm also curious to see better solutions.

Another FMC question: What do you do for parity? I just did a solve with 21 moves that left two edges and four corners off; how would you deal with that?

Here's the scramble and solution, if anyone's interested:

D' L2 F2 R' F L F' L2 D R D2 R F2 U' L2 D' R' U2 B2 R D2 U F2 R' D2

2x2x2: F D2 R U [4]
Another 2x2x2: B2 L' D' L [8]
More blocks: R F' R F U F R U' B U B' U' R [21]

The U' B U B' is in there because I don't know how to handle edges that are in the correct place bur oriented incorrectly; any advice on that?

 

[Mike Hughey]

(incidentally, I'm using Post-It notes instead of stickers; is this allowed in competition?)

I'm using Post-It notes (pieces of them I cut out with scissors) as my stickers too. The rules say you can use colored stickers:
E3) The competitor may use the following objects: paper and pen (both supplied by judge), 3 cubes (self supplied), unlimited coloured stickers (self supplied).

The rules don't say anything else about the "coloured stickers"; since Post-It notes are in fact colored stickers, I assume they should be valid. I asked once before on here what other people used, and no one answered. Maybe someone will answer now - what do other people use for colored stickers for fewest moves?

As for your other questions, I think you're now over my head. I could work on it a while and try to come up with something, but I doubt I'd be any better than you at it. I hope one of the experts (Per, Guus, Mirek, Arnaud, etc.) will chime in on this thread.

 

[Paiev]

I hate bumping threads, but there are quite a few questions in this one left unanswered. If someone could magically swoop in with answers in the next seven days before DC Open, I'd greatly appreciate it. Thanks.

 

[ch_ts]

I also found no good insertions with this scramble/solution. Sometimes you're just unlucky like that.

stickers: I'm using post-it notes too. I've never been to a competition but I'm sure that they're allowed.

Regarding your 2nd scramble: 4 corners + 2 edges is generally not very good unless you know algorithms for doing this in one step. 2 corners + 2 edges would be better if you could get it. Trying to do more than one insertion in a competition setting may not be very easy. Edges in their correct places but incorrectly oriented isn't so good.

However, this particular case isn't so bad. Do R' instead of R as your last move to make a pseudo-F2L. The corners are permuted relative to each other and the edges are oriented so this is one of the Petrus step6+7 cases. The solution I know for this one is U' (adjust the last layer) plus R'U'RU'R'U2R + RUR'URU2R' (two sunes) plus R2 to fix the pseudo-F2L which is 35 moves which is a pretty decent solution.