Understanding and Solving the Rubik's Cube Without Algorithms
6.c. Solving 3 edges of the 2nd layer
In this step, our objective is to solve 3 out of the 4 edges in the equator layer (intermediate layer).
To facilitate our understanding, let's rotate the cube from the previous figure so that the white face is facing downward, and the "unsolved corner" (pink) is positioned in front of us on the right, as shown in Figure 6.3.
We will utilize the column containing the "unsolved corner" and the upper layer to perform the "go, swap, and back" moves, as depicted in Figure 6.4.
Please note the following details:
The dark gray area represents the layer used for the "swaps."
The pink color denotes the column used for the back and forth movements.
The E (equator) and D (down) layers should be maintained.
During this step, almost all the edges in the equator layer (E) will be solved, except for the edge located in the back and forth "free space" column.
To solve an equator edge, follow these steps:
Rotate the equator layer (E) by performing a setup move. This maneuver will position the target position in the back and forth column.
Execute the "go" movement, which involves moving the desired edge from the equator layer to the upper layer. You can accomplish this by applying the R move (right face clockwise) or F' move (front face counterclockwise).
Perform the "swap" by rotating the upper layer, exchanging the desired edge with the corresponding cubelet in the target position.
Execute the "back" movement, which involves performing the R' move (right face counterclockwise) or F move (front face clockwise).
Undo the setup move to return the equator layer (E) back to its original position.
Refer to Figure 6.5 for a visual example. In this figure, the desired edge is located in the upper layer (U), and the target position for the edge is highlighted in pink. You can click play (▷) on Figure 6.5 to see the move sequence or click forward (⧐) to proceed step by step.
If the desired edge is already in the equator layer but in the wrong position, you can use the same approach mentioned earlier to bring it to the upper layer and then solve it as usual. The same principle applies if an edge is in the correct position but has flipped colors.
By the end of this step, your cube should resemble Figure 6.6, with the equator layer (E) solved except for one edge, and the down layer (D) solved except for one corner.
At this stage, you have successfully solved 57% of the Rubik's Cube.
App source: animcubejs.cubing.net/animcubejs.html