ARTICLE

XY-Wing Technique: Y-Shaped Branch Logic

Master the elegant XY-Wing strategy in Sudoku. Learn how three bi-value cells (Pivot and Wings) lock candidates and remove digits.

Unlike grid-pattern techniques such as X-Wing or Swordfish, XY-Wing utilizes candidate relationships across three bi-value cells (cells with exactly two candidates).

Structure of an XY-Wing

Pivot (Stem): A cell containing candidates [X, Y].
Wing A: Shares a unit with Pivot, containing candidates [X, Z].
Wing B: Shares a unit with Pivot, containing candidates [Y, Z].

Elimination Logic

The Pivot cell must take either X or Y:

If Pivot is X ➔ Wing A must be Z.
If Pivot is Y ➔ Wing B must be Z.

Conclusion: Either Wing A or Wing B MUST be Z!

Therefore, any empty cell that sees BOTH Wing A and Wing B simultaneously can safely have candidate Z eliminated.

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