4x4 algorithm

Sorry for the bump, I just didn't want to make a new thread since this one was still related to my first question.

Does anyone know the algorithm that swaps only 2 center faces, but also messes up the corners? I know there has been some talk about it, but it hasn't been posted as far as I've seen. Thanks :)
 
Feanaro said:
Does anyone know the algorithm that swaps only 2 center faces, but also messes up the corners? I know there has been some talk about it, but it hasn't been posted as far as I've seen. Thanks :)
Click to expand...

To swap UBR with UFR and Ubr with Ufr do:
(Rr) U (Rr)' U' (Rr)' F (Rr)2 U' (Rr)' U' (Rr) U (Rr)' (Ff)' F' R' u' R U2 R' u R U2 (Ff) F R' F' r' F R F' r

This affects nothing else on a 4x4x4 supercube but those mentioned pieces.

--edit--
slightly more efficient and still supercube safe in regards to the other pieces of the cube.
(Rr) U (Rr)' U' (Rr)' F (Rr)2 U' (Rr)' U' (Rr) U (Rr)' R' F' r' F R F' r2 B' R B r' B' R' B

--edit 2--
yet a bit shorter. This one swaps UFL with UFR and Ufl with Ufr. Supercube safe.
U (Rr)2 (Bb)2 (Rr) F (Rr)' (Bb)2 (Rr) F' D' f' D F2 D' f D F2 (Rr) L F' L' f' L F L' f

Chris
 
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cmhardw said:
Feanaro said:
Does anyone know the algorithm that swaps only 2 center faces, but also messes up the corners? I know there has been some talk about it, but it hasn't been posted as far as I've seen. Thanks :)
Click to expand...

To swap UBR with UFR and Ubr with Ufr do:
(Rr) U (Rr)' U' (Rr)' F (Rr)2 U' (Rr)' U' (Rr) U (Rr)' (Ff)' F' R' u' R U2 R' u R U2 (Ff) F R' F' r' F R F' r

This affects nothing else on a 4x4x4 supercube but those mentioned pieces.

--edit--
slightly more efficient and still supercube safe in regards to the other pieces of the cube.
(Rr) U (Rr)' U' (Rr)' F (Rr)2 U' (Rr)' U' (Rr) U (Rr)' R' F' r' F R F' r2 B' R B r' B' R' B

--edit 2--
yet a bit shorter. This one swaps UFL with UFR and Ufl with Ufr
U (Rr)2 (Bb)2 (Rr) F (Rr)' (Bb)2 (Rr) F' D' f' D F2 D' f D F2 (Rr) L F' L' f' L F L' f

Chris
Click to expand...

Thank you so much! This is exactly what I was looking for.

BTW, I'm planning to go to the Big Cubes Comp, so I'll se you there! Hopefully I'll have my 4x4 bld down by then :)
 
Can anyone please post an Algorithm that only swaps two center pieces. Preferably any two centers on the face and Up sides.

Assume that RGBYOW are the six colors and I have Yellow on top and Red on face then the cube looks like this

Up
WB
GY

Face
GY
GG

I want to swap the Green on Up with the Yellow on the face.

It should not mess anything up and be optimal and not Supercube safe
 
On your example, you can simply use niklaas the following way:

U2 r U' l' U r' U' l U'

Note that what this alg actually does is a 3-cycle (the third center involved is the upper-left G center on the front face). For parity reasons, you cannot perform a supercube-safe alg which swaps 2 centers and leaves anything else in place.
 
rahulkadukar said:
Can anyone please post an Algorithm that only swaps two center pieces. Preferably any two centers on the face and Up sides.

Assume that RGBYOW are the six colors and I have Yellow on top and Red on face then the cube looks like this

Up
WB
GY

Face
GY
GG

I want to swap the Green on Up with the Yellow on the face.

It should not mess anything up and be optimal and not Supercube safe
Click to expand...

x U2 l U' r' U l' U' r
 
Say it was the top right corner of the center front and center up face, the two you would want to switch. Do this.
I use this for 7x7 and it is very flexible. And 6x6. Switches 2 center pieces and everything stays the same but those 2. Think about how it works and you can do it for other centers.
b r b' U2 b r' b' r U2 r' and maybe an extra U2 at the end.

I figured this out, and use it.
 
"Parity" algorithms are beyond the scope of current optimal solvers, and must be found by hand. I'm sure cmowla will chime in here soon, and he knows much much much more on the subject than me, but you're not going to find a 'short' algorithm for what you're looking for. The algorithm is going to be longer than 3x3 PLL algorithms.
 
Feanaro said:
Bump again. Is there any shorter alg that could swap two centers and two corners? I need it for 4x4 blind so it needs to be relatively short
Click to expand...

Just learn to use commutators and include an already solved center in the cycle, creating the illusion that only 2 centers have been swapped.

For instance, if it appears that Ufl and Rbu must be swapped to solve the centers, you could cycle Rbu -> Ubr -> Ufl using the following commutator:

[r' u r, U2] --> r' u r U2 r' u' r U2

small letters indicate inner slices only

Mike Hughey made a post explaining how he solves 4x4 BLD using commutators. I recommend you read that.
 
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Feanaro said:
Bump again. Is there any shorter alg that could swap two centers and two corners? I need it for 4x4 blind so it needs to be relatively short
Click to expand...

The one I'm using is (I already posted it in another thread but I can't find it):
Fw2 Rw2 U' Lw2 U Rw2 U' Lw2 U Fw2 U' x' U L' U' l' U L U' l2 D' L D l' D' L' D x
It swaps the ULF and ULB corners and the Ulf and Ulb centers, leaving everything else in place. (The idea is to first swap two 1*2*2 blocks and then fix edges.)
 
Centre cubies or centres solved?

Man, look at that, my LEET post =)
LEET.jpg


Documentation, I will post more and then it will not be understandable.
 
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Yes, I later understood it is for classic Pochmann...

But still, an alg that swaps two solved centres and two corners can be useful if you have the two centres solved or near solved from the scramble.

r U2 r' l' U2 l is a nice start for that, then a little setup + T-PLL to do the rest.
 
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Feanaro said:
Bump again. Is there any shorter alg that could swap two centers and two corners? I need it for 4x4 blind so it needs to be relatively short
Click to expand...
This is the best I could do for right now (maybe forever):

Note: This is in SiGN notation, so click on the hyperlinks if you are not familiar with it.;)

r2 y r U l' u2 r U' 2R L2 x' 3d' 2R2 3d L' F' L 3d' 2R2 3d L' x U m U r2 y' (29q/23h)

I doubt the optimal algorithm is much shorter (if it's shorter at all). I hope you like it.


Also, note that the two double inner-layer turns can be converted to wide and affect 4 corners, but still swap just two x-center pieces:
r2 y r U l' u2 r U' 2R L2 x' 3d' r2 3d L' F' L 3d' r2 3d L' x U m U r2 y'
 
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