Orientate (Flip) Last (yellow) Edges
Orientate the yellow edges
(first part of the yellow cross)
Step 4: Yellow cross, first part. Flip edges (if necessary!)
Our goal in this step
When we have finished the second layers, the yellow edges can be in three different states (do not look at the corners in this stage at all!):
· All four yellow stickers are in the roof. Go to the next step
· no yellow stickers are in the roof; four edges need to be flipped
· two yellow stickers are in the roof; two need to be flipped
The nature of the cube does not allow that one or three stickers are on the roof. (If you ever see a cube with correct 2 layers and one or three yellow stickers on the roof, somebody has disassembled his cube and assembled it incorrectly.)
We learn our second algorithm: L, F, U, F', U', L' (algorithm II)
We analyze this sequence of moves
· We count six moves.
· Three layers are involved that meet at one corner (LFU).
· The first three moves are clockwise and involve the three different layers.
· The last three moves are anticlockwise and involve the same three layers in a different sequence
If all yellow edge stickers are on the roof, we do nothing and go the next lesson!
The two yellow stickers can come in two patterns: They build a line with the yellow centre, as in the example, or they build an L pattern.
Here are the six moves executed on a solved cube:
L
F
U
F’
U’
L’
Let’s cover the line case first:
We turn the U layer until the line goes from the F wall to the B wall.
We do our algorithm
How do we memorize this sequence best?
We do the first move along the yellow line, the second crosses the yellow line.
A memorizing sentence can be: the wall along, the wall across, the roof above, restore the wall, restore the roof, the first is restored at last.
If we ever forget it, it is still easy to remember that we have to do six moves, three clockwise, followed by three anticlockwise. The first two are wall moves, and the roof above them follows. If we reverse them in the wrong order it could be: L, F, U, U', F', L'. This would do nothing to the cube. As long as we remember the last move will restore the first, we should be able to recollect the algorithm.
If the two yellow edges build the L pattern, we turn the U layer until one yellow edge sticker is back and the other is right as in the picture to the right.
If we have no yellow edge stickers on the roof (like in this example),.
algo II
They build now the line. and we repeat our algorithm L, F, U, F', U', L'
We do our algorithm once and get this:
we do our algorithm once
Do not look at the corner stickers, just the edge stickers matter.
Again, we do not care about the yellow corner stickers at all. We recognize the L pattern, position it by U2
and solve it doing the algorithm twice: Done
