XYZ-Wing
AdvancedUsed at: Expert
A variant of XY-Wing where the pivot has three candidates. The pivot chains with two cells in the same box.
XYZ-Wing — Explained
XYZ-Wing is a close relative of XY-Wing, except the pivot has three candidates XYZ. If two cells in the same box carry XZ and YZ, then any cell that sees the pivot and both wings cannot contain Z, because Z would be forced into one of those three cells.
When to Use
Best used in advanced puzzles with full pencil marks, especially when many cells in one box interact and ordinary pair logic is no longer enough.
Common Mistakes
Treating any three related cells as XYZ-Wing. The pivot must have exactly three candidates, the wings must be bivalue, and the elimination cell must see all required cells.
Tips
Scan crowded boxes for a trivalued pivot first. Once you find XYZ, check whether two bivalue partners split the same Z candidate into XZ and YZ.
XYZ-Wing Steps
Find the pivot
Find a cell with three candidates (XYZ). This is the pivot.
Find the wings
In the same box, find cells with XZ and YZ candidates.
Eliminate Z
Eliminate Z from cells that see the pivot and both wings.