XY-Wing
Short answer: find a cell with exactly two candidates — the pivot — and two more two-candidate cells it can see. Each wing shares one shape with the pivot and both share a third shape with each other. Whatever the pivot turns out to be, one of the wings is forced to be that third shape, so no cell seeing both wings can hold it.
What an XY-Wing looks like
Three cells, two candidates each, no shape appearing in all three. Written out, the pivot is XY, one wing is XZ and the other is YZ. The pivot must be X or Y; if it is X the second wing must be Z, and if it is Y the first wing must be Z. Either way a Z appears in one of the wings.
The pivot never gets solved by this, and neither do the wings. The whole point is what happens somewhere else — in the cells both wings can see, which are often nowhere near the three cells you were looking at.
How to use an XY-Wing
- Start from a two-candidate cell. Pick any cell with exactly two candidates and treat it as the pivot. Cells with two marks are the raw material for every wing and chain technique, so it pays to notice them as you go.
- Find two wings it can see. Look for two more two-candidate cells the pivot shares a row, column or box with. One must share the pivot’s first shape, the other its second, and both must carry the same third shape.
- Check the wings do not repeat the pivot. The three cells must use exactly three shapes in total. If all three cells share a shape, or a wing duplicates the pivot exactly, the argument does not hold.
- Strike where both wings can see. Remove the shared wing shape from every cell that sees both wings. The wings do not need to see each other — only the target does the seeing.
If your pivot has three candidates rather than two, you may still have something: that is an XYZ-Wing, with a slightly tighter elimination. Wings are also the gateway to chains — a remote pair is the same idea run along a longer path.
XY-Wing vs X-Wing
The names look alike and the techniques have almost nothing in common. An X-Wing tracks a single shape across four cells in a rectangle, and the geometry is everything. An XY-Wing involves three different shapes across three cells, and the geometry barely matters — the cells just have to see each other in the right pattern. If you find X-Wings by scanning rows for one shape, you will never find an XY-Wing that way; the search starts from two-candidate cells instead.
Find XY-Wing in your own grid
Paste a puzzle and this page will look for XY-Wing in it — the same pattern shown above, in your grid instead of ours. Nothing is uploaded; it runs in your browser.
Frequently asked questions
Do the two wings need to see each other?
No, and usually they do not. Each wing has to see the pivot, and that is the only adjacency the pattern requires. What matters afterwards is which cells see both wings — those are the ones that lose the shape.
What if there is no cell that sees both wings?
Then the XY-Wing is real but useless, which happens often. The pattern only pays off when the wings are positioned so some cell shares a unit with both — typically when they sit in the same row, column or box as each other without being in it together.
Can the pivot have three candidates?
Not for a plain XY-Wing — it needs exactly two, because the argument is "the pivot is either X or Y". A three-candidate pivot gives you an XYZ-Wing instead, where the target must also see the pivot.
How do I get faster at spotting them?
Keep a mental list of the two-candidate cells as you fill the grid in. Almost every hard technique past this point — XYZ-wings, remote pairs, most chains — starts from them, so noticing them is a single habit that unlocks several techniques at once.