Step four: Orienting the Last Layer-edges

In this step, we will orient the yellow edge pieces (making a yellow cross on the top), using a sequence of six moves, and it’s inverse. In this step, we can ignore the positions of the yellow edge pieces, we will only pay attention to their orientation. There are four possible cases for this step. One of them is: all the top layer pieces are oriented correctly. In that case, you can move on to step five. In two other cases, two edge pieces need to be flipped, or all four edge pieces need to be flipped. Before I show you the algorithm, I will explain something about how the move works, because this will make it easier to memorize the moves. Take a look at this part of Lars Petrus page. Lars Petrus uses a different approach for solving Rubik’s Cube, but we can learn something important from his page. At this stage of his solution, a 2x2x3 block has been created. The basic idea of his method is to solve the rest of the cube, without breaking up the 2x2x3 block (off course, there are exeptions). In other words, the idea is to solve the cube by making R and U moves only. However, there is one problem: If there are flipped (or ‘bad’) edges, there is no way you can flip them by turning two sides only (applet 25). That’s why step three of his solution is to twist the edges the right way. The easiest way to do that, is to put two bad edges in the FR and UB positions, and do the moves RUR' (applet 26).

25. A flipped edge
26. RUR'


To flip the edges in UF and UB positions (applet 27), first do the move F. This puts the UF edge in the FR position. Then do the moves RUR’. These moves will flip the edges. Then solve the first two layers (F2L) in two moves: U’F’. When we put all these moves together, we get F R U R' U'F' = [A].

27. F R U R' U'F'


To flip the edges in the UF and UR positions, use the inverse of these six moves: FURU’R’F’ (denoted by [A]-1). To flip all edges in the U layer, do the moves [A]-1 U [A]. The applets below will illustrate the solutions for these two cases.

28. F (URU'R') F'
29. F (URU'R' F') - U - (F RUR'U') F'