--- title: "Finned X-Wing: An X-Wing with an extra possibility" description: "A Finned X-Wing adds a fin to the basic pattern. Remove only candidates that conflict with both the fin and the X-Wing left when the fin is false." lang: "en" canonical: "https://unisu-sudoku.app/en/sudoku-techniques/finned-x-wing/" --- [Back to the learning guides](https://unisu-sudoku.app/en/learn/) Advanced techniques # Finned X-Wing: An X-Wing with an extra possibility A Finned X-Wing adds extra candidates in one box, called the fin, to the basic pattern. An elimination must conflict both with the fin and with the X-Wing that remains if the fin is false. ![Unisu lesson on Finned X-Wing, showing the explained grid](https://unisu-sudoku.app/_astro/en.Bg7oGtCV_26k2Vd.webp) A Finned X-Wing adds extra candidates in one box, called the fin, to the basic pattern. An elimination must conflict both with the fin and with the X-Wing that remains if the fin is false. ## An example from the app Candidate 1 forms a rectangle in row 7, row 3 across column B, column E. The fins in A3 add extra positions, all in box 1. Without 1 in fins A3, the ordinary X-Wing applies. With 1 in a fin, box 1 blocks the same targets. Either way, 1 is ruled out in B2. These notes are therefore ruled out: B2: 1. 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 Targets are restricted to the fin’s box and the relevant cover line. This guide uses the supported non-sashimi form. 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 Finned X-Wing ### What is the fin in Finned X-Wing? An extra position for the digit beside the basic X-Wing. In the illustrated form, the fins share one box. ### Can I ignore the fin while looking for eliminations? No. The target must be excluded both when a fin holds the digit and when the ordinary X-Wing remains. ### Where may I eliminate in this example? At suitable positions of the cover line inside the fin’s box, outside the starting rows. Both cases exclude the digit there. ### Can any extra note serve as a fin? No. It must satisfy the required area and visibility relationships. An arbitrary extra candidate beside a rectangle is not enough. ### Does this explain every Sashimi form too? No. This introduction covers the supported non-Sashimi form. Do not transfer its eliminations to a different pattern without checking the logic. ## 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 ### X-Wing [Read more: X-Wing](https://unisu-sudoku.app/en/sudoku-techniques/x-wing/) ### Locked Candidates [Read more: Locked Candidates](https://unisu-sudoku.app/en/sudoku-techniques/locked-candidates/) ## 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)