#### Zarxrax

##### Member

1. If you see a "bar" then you have an adjacent swap permutation on that layer, on the pieces opposite the bar.

2. If all pieces on the layer are different colors, then you have a diagonal swap permutation.

3. This is the only situation that can be a bit hard to work out, but if you know the trick to it, its quite simple. If you see the same color on diagonally opposite corners (for example the 2 red faces in the top layer), then you have an adjacent swap. But, just looking at 2 sides, how do you know where the bar is located?

Just look for 2 opposite colors side-by-side. Here we can see the red and the orange beside each other. This tells us that these are the two pieces that need to be swapped. The bar is located opposite from them, on the back layer.

Adjacent swap and diagonal swap are the only permutation cases that can happen on the 2x2x2 cube. PBL solves them for both the top and bottom layers simultaneously.