W-Wing
Expert
Used by Smart Hint
Two cells with the same candidate pair, linked by a strong chain on one digit elsewhere on the board.
- First colour in the chain
- Cells that establish the pattern
- Where the conclusion lands
- Candidate ruled out
How it works
- A1 and I7 both carry the same candidate pair {4, 7}, but they don't share a row, column, or box, so they can't rule each other out directly.
- Column E has a strong link on 4: E1 and E7 are the only two candidates for 4 in that column, and each sits in the same row as one of the bivalue cells.
- That strong link forces one of A1 / I7 to be 4 and the other 7 — so 7 can be eliminated from I1, which sees both of them.