Ever since I published my cube solution, with my own unique notation for representing operations, I've been hearing something like this about once a week:

> I have a question on your notation regarding the moves > > D2-, D2*, and D2. > > What do these mean? Any help would be appreciated because I keep > getting stuck on flipping two adjacent bottom edges for the final > sequence. Thanks.

What's up, everybody? They make perfect sense to *me*. :)

The "2" refers to the 2nd level deep, relative to the face mentioned. I use this notation because it extends to arbitrary cube sizes (4x4x4, 5x5x5, and larger). On the 3x3x3 cube, it is simply the middle slab of the cube. When the face is D (or U), it refers to the middle horizontal layer.

The -, *, or + (or lack thereof) still refer to how far to turn the slice: quarter-turn counterclockwise, half-turn, or quarter-turn clockwise, respectively.

`D2-` has the same net effect as doing `{U-
D}` and then turning the whole cube a quarter-turn
counterclockwise relative to the bottom (which I would denote as
`D123-`, by the way). As you can see, this is a much more
concise way to write that, in addition to the extensibility
advantage that I mentioned above..

## D2 (also U2): |
## R2 (also L2): |

+---+---+---+ / / / /| +---+---+---+ + / / / /|/| +---+---+---+ +#+ / / / /|/|/| +---+---+---+ +#+ + | | | |/|/|/ +---+---+---+#+ + |###|###|###|/|/ +---+---+---+ + | | | |/ +---+---+---+ |
+---+---+---+ / /###/ /| +---+---+---+ + / /###/ /|/| +---+---+---+ + + / /###/ /|/|/| +---+---+---+ + + + | |###| |/|/|/ +---+---+---+ + + | |###| |/|/ +---+---+---+ + | |###| |/ +---+---+---+ |

Tom Magliery

tom@magliery.com