Third layer edge permutation - swap two pieces across?

[RN13]

Hello,

I am using this method for solving the last layer:

Edge Orientation (EO)
Edge Permutation (EP)
Corner Permutation (CP)
Corner Orientation (CO)

After creating/orienting the yellow cross - for the edge permutation I am using the algorithm: R U Ri U R U U Ri U to swap two edge pieces that are next to each other.

However, sometimes I need to exchange two edge pieces that are opposite of each other. This is possible by doing the above twice, but I am wondering if there is any algorithm that could do this in one action?

That is: the corner pieces does not matter, but swap two opposite edge pieces that are correctly oriented?

 

[Smiles]

Yes, we call this algorithm T permutation.
R U R' U' R' F R2 U' R' U' R U R' F'

edit: judging by your notation, note that R2 = R R and U' = Ui.
and this should go in the Request an Alg thread or 3x3x3 One Answer Question thread.

edit: removed J perm lol

 

[RN13]

Yes, we call this algorithm T permutation.
R U R' U' R' F R2 U' R' U' R U R' F'

Thanks a lot for your quick reply. This seems to do what I need, i.e. a cross swap of two edge pieces, great!

One question, what is the T in this?

Or there is the J permutation.
R U R' F' R U R' U' R' F R2 U' R'

When trying this out it seems to get another result than above, is that correct?

 

[Seanliu]

Thanks a lot for your quick reply. This seems to do what I need, i.e. a cross swap of two edge pieces, great!

One question, what is the T in this?



When trying this out it seems to get another result than above, is that correct?

One is a J-Perm, and one is the T. The T swaps opposite edges, but the J swaps adjacent edges. And yes, they are different.

 

[SenorJuan]

Or there's these two:
FRUR'U'F' R'U'F'UFR
and
R'F'U'FUR FURU'R'F'

 

[RN13]

One is a J-Perm, and one is the T. The T swaps opposite edges, but the J swaps adjacent edges. And yes, they are different.

So J-Perm (R U R' F' R U R' U' R' F R2 U' R') is the same as this, or?

R U R' U R U2 R' U

If so, the J seems more complex?

 

[PenguinsDontFly]

So J-Perm (R U R' F' R U R' U' R' F R2 U' R') is the same as this, or?

R U R' U R U2 R' U

If so, the J seems more complex?

J perm also swaps the two corners on the right. If all corners are oriented and you want to solve the adjacent edges, use J perm. If they are not oriented, use sune.

 

[RN13]

Or there's these two:
FRUR'U'F' R'U'F'UFR
and
R'F'U'FUR FURU'R'F'

Thanks for these as well!

J perm also swaps the two corners on the right. If all corners are oriented and you want to solve the adjacent edges, use J perm. If they are not oriented, use sune.

Ok, that seems logical.

What does the "T" mean in the name of the algorithm? The pieces move like a I and not T?

 

[AlphaSheep]

They get their names from the way they affect corners and edges. If you perform them on a solved cube, (blue in front yellow on top) then you get the following:

J-perm:

T-perm:

 

[RN13]

Ah, nice, I did not observe that the corner pieces moved together with the opposite edge pieces.

 

[Smiles]

whoops, sorry for giving you a J perm.
J perm does not do what you want. i totally messed up there haha my bad.

 

[RN13]

No problem, I was just confused for a while as it did not change the pieces I wanted.

 

[PenguinsDontFly]

Yeah to move 2 edges you have to also swap two corners.

 

[RN13]

Yeah to move 2 edges you have to also swap two corners.

Interesting. It is something "physical" that makes this mandatory?

 

[Berd]

Interesting. It is something "physical" that makes this mandatory?

You just can't - math n stuff I think.

 

[Julian]

Interesting. It is something "physical" that makes this mandatory?

It's essentially pretty simple. Any sequence you can do is a combination of quarter moves. A single quarter move cycles 4 edges around in a circle and 4 corners around in a circle. This adds up to an even total number of edge swaps and corner swaps.

Also, for your original question, T- and J-perm are good, but something else you can do is just do your adjacent swap algorithm (which is called 'sune') from any angle, even if you have an opposite swap. Then, after adjusting the U face, you'll just have an adjacent swap, so you do the sune again. Up to you which you like better.

 

[RN13]

It's essentially pretty simple. Any sequence you can do is a combination of quarter moves. A single quarter move cycles 4 edges around in a circle and 4 corners around in a circle. This adds up to an even total number of edge swaps and corner swaps.

Thanks for the explaination, I guess that makes sense.

Also, for your original question, T- and J-perm are good, but something else you can do is just do your adjacent swap algorithm (which is called 'sune') from any angle, even if you have an opposite swap.

I have been solving the permutation of the yellow cross earlier by using either one or two "Sune", but I was looking to see if there was any faster way to handle the situation with two opposite pieces correct and the other edge pieces inverted. I think the T-perm would be a good tool in those situations.

Sligthly off-topic, but it is a bit fun that the "Sune" algorithm is named from a kind of older male name in my country, Sweden.

 

[stoic]

I think it was Lars Petrus who named the Sune.
Also Niklas and Bruno...

 

[RN13]

I think it was Lars Petrus who named the Sune.
Also Niklas and Bruno...

Niklas is a very common swedish name, while Bruno might exist, but quite uncommon even in older days.