Y-Wing - A Three-Cell Chain That Creates Clean Eliminations
Y-Wing is a classic candidate-chain technique used in expert sudoku. It relies on three bivalue cells, meaning each of the three cells contains exactly two candidates. One cell acts as the pivot. The other two are pincers that each share one candidate with the pivot. The pincer cells do not need to see each other, but any target cell that sees both pincers can lose the candidate they share.
It sounds theoretical, but the logic is elegant: no matter which value the pivot takes, one of the pincers will force the shared candidate, which means the shared candidate cannot remain in any cell that sees both pincers.
How to Recognise the Pattern
Suppose the pivot is {2, 7}. One pincer is {2, 9} and another is {7, 9}. The two pincers share 9. Any cell that can see both pincers cannot keep 9, because whichever value the pivot resolves to, one pincer will end up forcing 9.
Why Y-Wing Matters
Y-Wing is often the point where players realise sudoku is no longer about local scanning alone. The technique rewards clean pencil marks and patient chain tracing. If you are working through Expert Sudoku, Y-Wing is one of the patterns that stops the board from stalling completely.
Frequently Asked Questions
What is a Y-Wing in sudoku?
It is a three-cell chain with one pivot and two pincers, used to eliminate a shared candidate.
When should I look for Y-Wing?
Look for it in expert puzzles when many cells have exactly two candidates.
Is Y-Wing harder than X-Wing?
Usually yes, because it is less visual and depends on chain logic instead of a geometric rectangle.
Next Steps
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