Daily F2L Discussion - Case 3

Case 3

Setup: F' U F

Most important solution: y' R' U' R

Angles: Easy from FL + BR. Harder from FR + BL.

Mirror: Case 4

Discussion: This is one of the four most fundamental cases (along with cases 1, 2, and 4), as most F2L cases are solved by reduction to cases 1-4. Cases 3-4 are examples of "flip cases," as they are solved by flipping the corner toward its matching edge and inserting the resulting pair.

The solution is trivial, but there is a lot to learn from studying this case. Here are a few things to keep in mind:

1. "Flip cases" arise when the top sticker of both the edge and corner pieces are different (and the corner's cross color is not on top)

2. The corner can be flipped toward an edge in one of two ways (R or F', in this case), but only one of these is ever correct. You must always flip the corner along its "line of action." The line of action, as RiDo explains in his fantastic F2L video, is an imaginary arrow that is formed by connecting the two non-white stickers of the corner (red and blue, in this case). If you try to flip the corner along the incorrect direction, then you'd end up with a white sticker on top (which will never form an F2L pair if you're solving the white cross).

3. Ideally, the line of action will point toward the corresponding edge (cases 3-4). If the line of action points toward an incorrect edge (cases 9-14), then you must reposition the edge to set up either case 3 or 4.

4. You must make sure that the corner is above its empty F2L slot before you initiate the flip. Otherwise, you will insert the F2L pair into an incorrect slot!

5. In general, it's better to solve this case into the back (BR). Not only is the solution <R, U>, but it leaves you with two potentially unsolved F2L slots in the front, where they are fully visible.

If you understand this case intuitively, then you should also be able to handle many cases (from many angles) in which either a corner piece or an edge piece is stuck in an F2L slot. I will talk more about these cases as they come up sequentially.

Algorithms

Front Right (FR)

y' + {BR}

y + {FL}

F' U' F

[Back Left (BL)](http://cube.crider.co.uk/visualcube.php?fmt=png&size=200&stage=f2l&case=y2F' U' F.png)

y' + {FL}

y + {BR}

[Front Left (FL)](http://cube.crider.co.uk/visualcube.php?fmt=png&size=200&stage=f2l&case=y'F' U' F.png)

L' U' L

[Back right (BR)](http://cube.crider.co.uk/visualcube.php?fmt=png&size=200&stage=f2l&case=yF' U' F.png)

R' U' R

Previous Daily F2L Discussions

1 2 3