XY-Wing: connect two wings through a pivot
An XY-Wing uses a pivot with candidates XY and two visible wings XZ and YZ. The wings do not need to see each other.
Key idea
Whichever value the pivot takes, one wing must contain Z. Any cell that sees both wings therefore cannot contain Z.
See the move, step by step
Use R1C3 as the 5/7 pivot and candidate 6 as the shared wing digit.
Step 1 of 4
Find three connected bivalue cells
Start with pivot R1C3 and inspect peers that share one pivot digit.
Step 2 of 4
Label the pivot and wings
R1C3 is 5/7, R1C4 is 5/6, and R2C3 is 6/7. The two wings share candidate 6.
Step 3 of 4
Find a cell that sees both wings
R2C4 sees both R1C4 and R2C3, so one of those wings will always block its 6.
Step 4 of 4
Apply only the shared consequence
Remove 6 from R2C4 while leaving the three wing cells unresolved.
Try it on today's puzzle
Write each bivalue cell as a pair. A valid XY-Wing has three total digits, with each wing sharing one different pivot digit and the same elimination digit.
Play today