Understanding and Solving the Rubik's Cube Without Algorithms
In the previous cited example, it is not only possible to perform the swap but also to place the desired cubelet with its colors in the correct orientation. Refer to Figure 5.7, where the corner with the correct colors to replace the green cubelet is in position.
To proceed, we need to do a "setup" move. The question is, which setup option is better: D or D'? Let's test both cases to see what happens.
First, let's use the D move for the setup. Click forward (⧐) in Figure 5.7. Notice that the only option remaining for the "go, swap and back" sequence is to use the F layer as the back and forth layer:
F ("go")
D' ("swap")
F' ("back")
Click play (▷) in Figure 5.7 to see the result.
The desired corner has gone to the correct place but is twisted, meaning the colors are not in the correct orientation. This indicates that using D for the setup is not a good choice.
Let's go back to the initial condition and try D' for the setup instead. Click forward (⧐) in Figure 5.8. Again, notice that there is only one option left for the back and forth movement, using the R layer:
R' ("go")
D ("swap")
R' ("back")
Click play (▷) in Figure 5.8 to see the result.
This time, not only did we get the corner in the correct place, but it is also oriented correctly with its colors.
When considering the back and forth layer, in this example, there are two options: F or R layer. If we want to use the F layer, we remove the desired cubelet from that layer during the setup. On the other hand, if we want to use the R layer, we remove the desired cubelet from that layer during the setup.
Click play (▷) in Figure 5.9 to see the "setup" for the F layer (marked in pink) selected as the back and forth option.
Similarly, click play (▷) in Figure 5.10 to see the "setup" for the R layer (marked in pink) as the back and forth option.
Note that having the desired corner right under the place where we want to place it allows us to decide the best setup. The "back and forth" with the F layer will bring the yellow face up, while the "back and forth" with the R layer will bring the blue face up. In this case, the best option is to use the R layer for the back and forth move. Therefore, the best setup is D'. By foreseeing what the "back" movement will produce, you'll know what to do.
Before proceeding with "go, swap and back" moves, consider the following tips:
Bring the desired cubelet right under where it should be placed.
This will help you make a decision on the best setup.
The final result will be a cubelet in the correct place and correct orientation.
Now it's your turn to practice. Try performing "go, swap and back" moves, swapping pieces, and observing how the colors of the desired cubelets change orientation. With observation and practice, you will not only be able to make the swaps but also place the swapped cubelet with its colors correctly oriented.
To enhance your training, scramble the cube and attempt to solve a single layer without worrying about the rest of the cube, applying the principles learned so far. You can use the virtual cube below or by clicking here.
App source: animcubejs.cubing.net/animcubejs.html