--- title: "W-Wing: A matching pair joined by a strong link" description: "A W-Wing links two cells with the same candidate pair through a strong link. Follow the example to see how that connection rules out another candidate." lang: "en" canonical: "https://unisu-sudoku.app/en/sudoku-techniques/w-wing/" --- [Back to the learning guides](https://unisu-sudoku.app/en/learn/) Further techniques # W-Wing: A matching pair joined by a strong link A W-Wing starts with two cells containing the same two candidates. A strong link for one candidate connects them so that at least one cell must contain the other digit. ![Unisu lesson on W-Wing, showing the explained grid](https://unisu-sudoku.app/_astro/en.BsHfklH__1oJzhw.webp) A W-Wing starts with two cells containing the same two candidates. A strong link for one candidate connects them so that at least one cell must contain the other digit. Two cells see each other when they share a row, column or 3×3 box. An elimination needs the specific visibility relationships described in the reasoning. ## An example from the app H7 and A8 both have only 1, 3. Also, 1 has exactly two places in row 4: A4 and H4. The solid line connects those two possibilities. 1 must be in A4 or H4. This removes it from at least one of H7 and A8, forcing that cell to be 3. Cells sharing a row, column or box with both cannot contain 3. These notes are therefore ruled out: G8: 3. The image shows the candidates relevant to this step. A note being hidden does not mean it has been logically eliminated. ## Practice the next step Matching pairs alone are not enough. You need the actual strong link and a target that sees both end cells. In the app, follow the reasoning in the matching lesson and try a task yourself. With a new puzzle, always start from its actual candidate state. ## Questions about W-Wing ### Are two cells with the same pair sufficient? No. W-Wing also needs the appropriate strong link for one digit of that pair. ### What does strong link mean here? An area has exactly two positions for the linking digit. At least one of those positions must contain it. ### Must the two end cells see each other? Not necessarily. Their relationships to the strong link, and the target’s view of both ends, are what matter. ### Which digit of the pair is eliminated? The other digit, rather than the one used by the strong link. Remove it only from valid targets seeing both ends. ### Is W-Wing the same as XY-Wing? No. W-Wing links two identical pairs through a strong relationship. XY-Wing uses a pivot and two wings with different pairs. ## Keep practicing in Unisu Download Unisu for iPhone or Android. Solve a puzzle or work through a guided lesson on the technique. - [Download on the App Store](https://apps.apple.com/us/app/id6775824061?l=en) - [Get it on Google Play](https://play.google.com/store/apps/details?id=app.unisu.sudoku&hl=en) ## Useful before this guide ### XY-Wing [Read more: XY-Wing](https://unisu-sudoku.app/en/sudoku-techniques/xy-wing/) ### Hidden Single [Read more: Hidden Single](https://unisu-sudoku.app/en/sudoku-techniques/hidden-single/) ## Where to go next Advanced techniques Unisu · Oct 27, 2026 ### [XY-Chain: Link cells with two candidates](https://unisu-sudoku.app/en/sudoku-techniques/xy-chain/) An XY-Chain links cells with exactly two candidates each. Follow the example to see where the shared digit at the two ends can be eliminated. Unisu ### [Learn Sudoku: a path from rules to techniques – Unisu](https://unisu-sudoku.app/en/learn/) Start with the rules, get comfortable with pencil marks and choose a technique for the situation you’re working on. Download app ## Ready for a puzzle? Take a moment. Download Unisu on your phone. Start a Sudoku or choose a lesson on the technique you want to understand. - [Download on the App Store](https://apps.apple.com/us/app/id6775824061?l=en) - [Get it on Google Play](https://play.google.com/store/apps/details?id=app.unisu.sudoku&hl=en) ![The daily challenge in Unisu](https://unisu-sudoku.app/_astro/en.C-sYR9hJ_1QwI9G.webp) ![A classic Sudoku game in Unisu](https://unisu-sudoku.app/_astro/en.C6DJ1kiE_2dRWDN.webp)