I recognize PLL with a combination of “Blocks” and “Bars” A block is two or three connected pieces, like so:
A bar is a set of connected corners. I’ve put bars in red wherever possible. The term “bar” is taken from 2×2 PBL recognition, so a bar may or may not include the edge in between the corners. (If it does, it’s also a 1×3 block):
You can tell the permutation of a layer (and its parity) by comparing blocks and bars in most cases. I’ve included some lookahead information for square-1 permutation, but the recognition part applies equally to 4×4 PLL. Listed is which EP case each permutation goes to with a proper Vandenbergh solution, and then information on 1-look permutation if it applies.
The E/X/Q cases are difficult to recognize with this technique, so I’ve added some notes to the end of the page detailing how I recognize these cases.
| Permutation | Recognition | Corner Permutation | Resulting EP | 1-look Permutation | ||
| No parity: | ||||||
| U | + | J | = | U | J 1 J | |
| Z | + | J | = | Z | N/A | |
| H | + | J | = | H | N 1 N | |
| A | + | J | = | U | J 2 J | |
| T | + | J | = | U | J 4 J | |
| Ga | + | J | = | U | N J | |
| Gb | + | J | = | U | J N | |
| J | + | J | = | Solved | J or J J or J N or N J | |
| R | + | J | = | U | N/A | |
| F | + | J | = | U | N/A | |
| Y | + | N | = | U | J 5 J | |
| V | + | N | = | U | N/A | |
| N | + | N | = | Solved | N or J 6 J | |
| E | + | N | = | Z | N/A | |
| Parity: | ||||||
| Opp Edges | + | Solved | = | Opp | N/A | |
| Adj Edges | + | Solved | = | Adj | N/A | |
| O | + | Solved | = | O | N/A | |
| W | + | Solved | = | W | N/A | |
| Opp Corners | + | N | = | Opp | N/A | |
| Adj Corners | + | J | = | Adj | N/A | |
| K | + | J | = | Adj | N/A | |
| P | + | J | = | Opp or Adj | N/A | |
| B | + | J | = | Adj | N/A | |
| D | + | J | = | Opp | N/A | |
| C | + | J | = | W or O | N/A | |
| M | + | J | = | W | N/A | |
| S | + | N | = | Adj | N/A | |
| X | + | N | = | O | N/A | |
| Q | + | N | = | O | N/A | |
Notes on E/X/Q:
These are definitely the hardest to distinguish. The trick is to look at two edges, and the corner between them, and apply the 3-color rule. If there are 3 colors, that means EP is correct, so you have an E-perm. If there are 2 colors, you have an X, and if there are 4 colors, you have a Q.
| E | |
| X | |
| Q |