XY-Wing practice sheets
Three cells with two candidates each, arranged as a pivot and two pincers. Whatever the pivot turns out to be, one pincer carries the third digit.
The move that looks like nothing
An XY-Wing is three cells. Each holds exactly two candidates. One of them, the pivot, shares a unit with each of the other two. The pivot's two digits are X and Y; one pincer is X and Z; the other is Y and Z.
The argument is short: the pivot is either X or Y. If it is X, the pincer holding X and Z must be Z. If it is Y, the other pincer must be Z. Either way, Z is placed in one of the two pincers — so Z can be eliminated from any cell that sees both pincers at once.
Nothing about that is visual, which is why XY-Wings are easy to explain and hard to find. There is no rectangle to recognise, no line to follow. You are looking for three bivalue cells that happen to share a digit with each other and with a common target.
Why a dedicated sheet
In mixed sets an XY-Wing turns up at the point where a puzzle has already defeated singles, pairs and fish. You meet it in a bad mood, once. Here it is the thing every puzzle is built around, so the search becomes mechanical: find bivalue cells, look at their pairs, check the sees-both relationship.
Every puzzle is generated and then replayed with the cheapest technique first; it is kept only if an XY-Wing appears on that path. The filter runs in your browser, so the set is new on every visit.
What the grader guarantees
Every puzzle needs at least one XY-Wing, and nothing on the sheet asks for more than one tier above it — the hardest extra step you can meet is a swordfish, a W-Wing or a chain. That is expected, not a defect: the point of the sheet is the XY-Wing, and the rest is the difficulty ladder doing its job.
Making the search mechanical
- Collect the bivalue cells first. Before looking for a pattern, mark every cell with exactly two candidates. This is the raw material, and there are usually only a dozen.
- Try each as a pivot. For a cell holding X and Y, look in its row, column and box for a cell holding X and Z, and another holding Y and Z.
- Check that the two pincers see each other's targets. The elimination only happens where a cell sees both pincers. If nothing sees both, the XY-Wing is real but useless in this position.
Step 1 is the part people skip. Without printed marks, building the bivalue list means reading nine candidate lists per cell, and most players give up halfway and guess.
Printing it
Scale 100%, A4 or Letter. Candidate marks on is close to mandatory here — this technique is defined entirely in terms of candidate pairs. One puzzle per page is the version to learn on; four per page is the version to drill.
Related practice
The full guide to XY-Wing walks a real position, including the case where two pincers both look right and only one pair actually sees a common cell. XYZ-Wing is the three-candidate version of the same argument.
Other sheets: X-Wing, skyscraper, swordfish.