for 2 look pll why do u only need 1 corner cycle

[hugorocks123]

every website only list counter or clockwise corner cycle why doesnt any list both!!?!??

 

[Dene]

If you do either clockwise or anticlockwise twice it will get to the other case. So you only need one or the other, but both are preferable in the long term.

 

[Tim Reynolds]

If you're doing corner permutation before edge permutation, you can do a counter-clockwise corner cycle by doing a single clockwise corner cycle.

To cycle UFL-UBR-UBL, do U2 y2 R' F R' B2 R F' R' B2 R2.

 

[kjcellist]

Some websites do have both.

Example: http://www.cubewhiz.com/pll.html

 

[JTW2007]

I think I understand your question. For a corner cycle, you only need one algorithm, because you can either do it twice (easy) or mirror it (better) to get the other cycle. It's still the same alg, just reflected.

EDIT: This was my 600!

 

[riffz]

If you perform perform a conter-clockwise corner cycle when a clockwise one is necessary, you'll be left with some sort of edges-only permutation that you know.

 

[eragg0]

on 2-look PLL you first permute corners. there is no point to have both (CW and CCW) algs becouse only target is to get job done

 

[Spaniard]

Seriously you don't find both? In all the websites I've visited I've seen both. If you have the clockwise, do the inverse and you'll have the anticlockwise.

 

[eamsch]

this one has both:

http://badmephisto.dyndns.org/site/pll.php

 

[jacob15728]

It's because you don't use it for cycling corners. It's used for getting to cases you do know from cases you don't. Because either one would work the same way, you only need one.

 

[Ethan Rosen]

Why not just use a J/T perm?

 

[blgentry]

As several have said, there are definitely sites that list both algs, and once you move on a bit, you are going to want to know both. That being said, here's why some systems only teach you one of the corner cycles:

By following a mindless rule, you can always position the top layer such that a clockwise corner cycle will solve either the clockwise case, or the anti-clockwise case. Note that you will need to adjust the top layer in one of those two cases, as your matching corner may no longer match when you are done.

The "mindless rule" is to find the two corners showing the same color on the side, and put them on the back side of the cube.

If it's not clear, this works because in one case you are cycling one set of corners clockwise and in the other case you are cycling a different set of corners clockwise, which is equivalent to cycling the original corners anti-clockwise *plus* an adjustment of the upper layer (U face).

All this being said, I still don't like that method. I'd rather match one corner, see the case and run either the CW corner cycle or the ACW corner cycle as appropriate.

Brian.

 

[jacob15728]

Why not just use a J/T perm?

From my experience the A can be executed more quickly.

 

[AvGalen]

There are 21 pll's. If you split PLL in two steps (first permute corners, then permute edges) you can divide these PLL's in 3 groups:
Group 0: PLL's that only change edges (H, Ua, Ub, Z). You use these for permuting edges
Group 1: PLL's that swap 2 adjacent corners (Aa, Ab, F, Ga, Gb, Gc, Gd, Ja, Jb, Ra, Rb, T)
Group 2: PLL's that swap 2 opposite corners (E, Na, Nb, V, Y)

For 2 look pll (permute corners, permute edges) you actually need to learn 1 alg from Group 1 and 1 from Group 2 to permute corners. You also need to learn all 4 algs from Group 0 to permute edges.

The reason that you can perform an A-perm (3-cycle) to swap two adjacent edges is because you don't care about the edges. You can easily test this on a 2x2x2. Just do an A-perm and then a U or U' so you can easily see that 2 adjacent corners are swapped. Obviously Swapping just 2 corners isn't really possible on a 3x3x3 but again, you don't care about that because you are performing a corner-only step at that moment