X-Wing

Level: Intermediate

A rectangle pattern where a number's candidates in two lines fall in exactly the same two cells.

An X-Wing forms when, across two rows, the candidates for a specific number fall in exactly the same two columns (the four cells form a rectangle).

That number must go in two diagonal cells of the rectangle, so you can eliminate it from the other cells (outside the rectangle) in the two related columns. The same holds with rows and columns swapped.

It's the first advanced pattern spanning multiple lines, and it trains you to view the candidate grid more broadly.

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