I looked at your proposal. I don't know a direct solution, I'd do an L-pattern and then a 3-perm. If you chose the right algorithms, the cancellation is insane here!
B2 L2 B2 L2 B2 L2 B2 R2 F2 D2 B2 U2 L2
L2 U2 L2 F2 U2 L2 B2 L2 (y x') B2 R2 U2 R2 B2
// original:
// L2 U2 L2 F2 U2 // your first part
// (L2 B2)3 // L-pattern
// yx' (R2 U2 R2 B2)2 // 3-perm
I originally inserted this as 3-perm:
yx' (L2 U2 L2 B2)2
But I realized I can use the mirrored version for a LOT of cancellation!
Is L2 B2 L2 (y x') B2 R2 U2 R2 B2 the shortest solution to this case? Honestly, I don't know. But I keep this in mind if I run into this exact pattern again!
I looked at your proposal. I don't know a direct solution, I'd do an L-pattern and then a 3-perm. If you chose the right algorithms, the cancellation is insane here!
B2 L2 B2 L2 B2 L2 B2 R2 F2 D2 B2 U2 L2
L2 U2 L2 F2 U2 L2 B2 L2 (y x') B2 R2 U2 R2 B2
// original:
// L2 U2 L2 F2 U2 // your first part
// (L2 B2)3 // L-pattern
// yx' (R2 U2 R2 B2)2 // 3-perm
I originally inserted this as 3-perm:
yx' (L2 U2 L2 B2)2
But I realized I can use the mirrored version for a LOT of cancellation!
Is L2 B2 L2 (y x') B2 R2 U2 R2 B2 the shortest solution to this case? Honestly, I don't know. But I keep this in mind if I run into this exact pattern again!
By mirrored version, I mean mirrored version of the 3-perm:
(L2 U2 L2 B2)2
versus:
(R2 U2 R2 B2)2
(mirrored across the yz plane)
Both do the same, but if the previous patterned ended up with R2, or even better, U2 R2, or even more... (considering the y x' move here), then the second is much better than the first.
I'm gonna put into spoiler how I did it, because it contains a trick I haven't used so far!
Original:
B2 L2 B2 L2 U2 D2 L2 F2 D2 L2 F2 L2 F2
// original:
B2 U2 R2 // corners
(R2 E2)2 // H-pattern
(R2 U2 R2 B2)2 // 3-perm
Now with cancellation, but watch the E2 in the middle!
B2 L2 B2 L2 U2 D2 L2 F2 D2 L2 F2 L2 F2
// original cancellation, but then I noticed I can remove the (E2) and put it at the end...
B2 u2 R2 (E2) R2 U2 R2 B2 R2 U2 R2 B2
// original:
// B2 U2 R2 // corners
// (R2 E2)2 // H-pattern
// (R2 U2 R2 B2)2 // 3-perm
B2 L2 B2 L2 U2 D2 L2 F2 D2 L2 F2 L2 F2
// This is just moved the (E2) to the end:
B2 u2 R2 R2 U2 R2 B2 R2 U2 R2 B2 (E2)
I did a couple of tries, and this looked promising:
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 U2 // corners
E2 S2 M2 // checkerboard pattern
(R2 S2)2 // H-pattern
z2 (L2 U2 L2 B2)2 // 3-perm
Naturally there are some neat cancellations between the patterns:
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 S2 r2 S2 R2 (S2) (z2) L2 U2 L2 B2 L2 U2 L2 B2
Normally I would stop here. But I recently started to look into mid-pattern turns, and look at that: you can place the second S2 (the one in parentheses) to the end of the solve, because it does not affect the pattern solving itself:
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 S2 r2 S2 R2 (z2) L2 U2 L2 B2 L2 U2 L2 B2 (S2)
This results the following collapse:
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 S2 r2 S2 (z2) U2 L2 B2 L2 U2 L2 b2
It's a good stopping point, ya? But that S2 r2 S2 bothered me in the middle. Can it also be put elsewhere? What if I leave it out completely?
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 (z2) U2 L2 B2 L2 U2 L2 b2
Oh, the end is interesting, it's almost a full H-pattern... But that syncs with the last moves! IF YOU LEAVE OUT THE LAST TWO STEPS:
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 (z2) U2 L2 B2 L2 U2 // L2 b2
That is just 3 moves!
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 (z2) U2 L2 B2 L2 U2 R2 B2 R2
But now there are a whole new set of cancellations!
F2 L2 U2 F2 L2 u2 (z2) U2 L2 B2 L2 U2 R2 B2 R2 // u2 (z2) U2 becomes (x2)
F2 L2 U2 F2 L2 (x2) L2 B2 L2 U2 R2 B2 R2 // L2 (x2) L2 becomes (x2)
F2 L2 U2 F2 (x2) B2 L2 U2 R2 B2 R2 // F2 (x2) B2 becomes (x2)
F2 L2 U2 (x2) L2 U2 R2 B2 R2
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
// FINAL:
F2 L2 U2 (x2) L2 U2 R2 B2 R2
// cancellation chain:
// F2 L2 U2 F2 L2 u2 (z2) U2 L2 B2 L2 U2 R2 B2 R2 // u2 (z2) U2 becomes (x2)
// F2 L2 U2 F2 L2 (x2) L2 B2 L2 U2 R2 B2 R2 // L2 (x2) L2 becomes (x2)
// F2 L2 U2 F2 (x2) B2 L2 U2 R2 B2 R2 // F2 (x2) B2 becomes (x2)
// F2 L2 U2 (x2) L2 U2 R2 B2 R2
I am still puzzled by this.
Edit: I checked with an Optimal Solver what would have been its suggestion, and the optimal is indeed 8 moves! Although it suggested a different one:
I did a couple of tries, and this looked promising:
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 U2 // corners
E2 S2 M2 // checkerboard pattern
(R2 S2)2 // H-pattern
z2 (L2 U2 L2 B2)2 // 3-perm
Naturally there are some neat cancellations between the patterns:
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 S2 r2 S2 R2 (S2) (z2) L2 U2 L2 B2 L2 U2 L2 B2
Normally I would stop here. But I recently started to look into mid-pattern turns, and look at that: you can place the second S2 (the one in parentheses) to the end of the solve, because it does not affect the pattern solving itself:
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 S2 r2 S2 R2 (z2) L2 U2 L2 B2 L2 U2 L2 B2 (S2)
This results the following collapse:
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 S2 r2 S2 (z2) U2 L2 B2 L2 U2 L2 b2
It's a good stopping point, ya? But that S2 r2 S2 bothered me in the middle. Can it also be put elsewhere? What if I leave it out completely?
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 (z2) U2 L2 B2 L2 U2 L2 b2
Oh, the end is interesting, it's almost a full H-pattern... But that syncs with the last moves! IF YOU LEAVE OUT THE LAST TWO STEPS:
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 (z2) U2 L2 B2 L2 U2 // L2 b2
That is just 3 moves!
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
F2 L2 U2 F2 L2 u2 (z2) U2 L2 B2 L2 U2 R2 B2 R2
But now there are a whole new set of cancellations!
F2 L2 U2 F2 L2 u2 (z2) U2 L2 B2 L2 U2 R2 B2 R2 // u2 (z2) U2 becomes (x2)
F2 L2 U2 F2 L2 (x2) L2 B2 L2 U2 R2 B2 R2 // L2 (x2) L2 becomes (x2)
F2 L2 U2 F2 (x2) B2 L2 U2 R2 B2 R2 // F2 (x2) B2 becomes (x2)
F2 L2 U2 (x2) L2 U2 R2 B2 R2
B2 R2 L2 F2 R2 B2 L2 D2 L2 U2 L2 F2
// FINAL:
F2 L2 U2 (x2) L2 U2 R2 B2 R2
// cancellation chain:
// F2 L2 U2 F2 L2 u2 (z2) U2 L2 B2 L2 U2 R2 B2 R2 // u2 (z2) U2 becomes (x2)
// F2 L2 U2 F2 L2 (x2) L2 B2 L2 U2 R2 B2 R2 // L2 (x2) L2 becomes (x2)
// F2 L2 U2 F2 (x2) B2 L2 U2 R2 B2 R2 // F2 (x2) B2 becomes (x2)
// F2 L2 U2 (x2) L2 U2 R2 B2 R2
L2 F2 L2 R2 U2 R2 // 123 (6)
B2 U2 F2 D2 // Cancellation into 2e2e (4/10)
Pretty sure this is optimal, lol. It there a thread of this for 4x4? Still got to watch the tutorial for this. Definitely interested in seeing the strats for 4x4
L2 F2 L2 R2 U2 R2 // 123 (6)
B2 U2 F2 L2 // Cancellation into 2e2e (4/10)
Pretty sure this is optimal, lol. It there a thread of this for 4x4? Still got to watch the tutorial for this. Definitely interested in seeing the strats for 4x4