Lars Petrus Method

 

3. Orientation of edges

 

(We moved the 2x2x3 block down back, so the scrambled parts are on the F and U sides.)

We orient the remaining seven edges. But first we have to make clear, what is a „bad” or a „good” edge. In this state we can only turn the F and U sides free (we will need to break up the solved parts), so the definition is: the edges’s orientation is good, if we can(could) put it in its place correct(so its stickers’ colors will match the sides’ colors) turning only the F and U sides. There’s a fast way to recognize this:

The edge’s prime color is the one which matches to one of the remaining center pieces’ colors. (Here: yellow and orange.)

 

1. The edge is correct, if it’s on its side and its prime color is beside the center piece.

2. The edge is bad, if it’s on its side but its prime color is not beside the center piece.

3. The edge is correct, if it’s not on its side and its prime color is not beside the center piece.

4. The edge is bad, if it’s not on its side but its prime color is beside the center piece.

 

 

Here’s an example:

 

 

I. egde is bad because of the 2. and the 4. rules. (This egde has two prime colors, but it’s enough to look at only one of them.)

II. edge is bad, because of the 4. rule.

III. edge is bad, because of the 2. rule.

IV. edge is good, because of the 1. rule.

V. edge is bad, because of the 4. rule.

VI. edge is good, because of the 1. rule.

VII. edge is good, because of the 3. rule.

 

Note: the number of the bad edges is always even. If it’s not, you have made a mistake somewhere.

The aim is to orient all of the edges. You can do this in twos, with temporarly breaking up the blocks. F.e.:

 

 

The two edges are bad. We can only fix their orientation by breaking up the block: L’ changes the orientation of the bottom edge, U’ exchanges the two edges, L orients the other edge and also builds the block back. So the alg is: L’UL.

Another example:

 

 

We can choose: FU and the way above, or F’ and RU2R’ (which is similar to the previous one), or the shortest: LFL’, which is the same as in the previous example, but upside down.

We can also combinate:

 

 

Four bad edges. LF’L’ fixes the first two, L’U2L the other two, so: LF’L2U2L.

 

If you want to learn the shortest way for every case (max 8 turns, but 5 on average), you can find them all on Lars’ page:

2 bad edges: http://www.lar5.com/cube/fas3_2.html (8 cases)

4 bad edges: http://www.lar5.com/cube/fas3_4.html (12 cases)

6 bad edges: http://www.lar5.com/cube/fas3_6.html (3 cases)

If you can’t recognize a case, rotate the cube: xy2.

 

 

 

Back to the Lars Petrus Method

Back to the 2x2x3 block

Go to the finishing of the first two layers