12/6/2023 0 Comments Xy wing sudoku strategy![]() Applying logic as you solve a puzzle will determine which cell will be solved by the. I only pencil in a candidate when it is limited to two cells in a row, column, or 3×3 region. It will be easier to understand this technique if you look at the example. You shouldnt pay attention to the 3x3 blocks as they arent involved in this strategy. You don’t need to pencil in all the candidates. '-wing' is an advanced sudoku technique, which is based on the two parallel rows or two parallel columns. I find this mistake (saying the above A, B should be "locked pairs") in the book "Extreme Sudoku for Dummies" by Andrew Heron & Andrew Stuart, so I check here, I hope this helps the discussion to go clear. All the free easy Sudoku puzzles on this website can be solved using this technique and pencilling in candidates. As a result, (B5, E2) could be (C, non-C), (non-C), or (C, C), and in all scenarios, C should be eliminated from cell E5. ![]() The cell in the center is called the pivot. Similarly, the two A's in cells B2 & E2 are not a "locked pair" either, there could be other A's in column 2. An XY-Wing is a solving technique that uses a short chain of 3 cells. Note that: the two B's in cells B2 & B5 are not a "locked pair", in other words, there could be other B's in row B. The statement "So whatever happens, C is certain in one of those two cells marked C.", which implies C in one of the two cells, actually C can also be in both cells. the XY wing is an extension of both of these Sudoku solving techniques, and. The definition of "see" is "two cells within the same element (row, column, box)" (the two cells see each other) In Lesson 10 and 11 of my 'lessons' series, I covered x wings and the swordfish. XY Wing involves 3 different cells each with exactly two candidates that are related to each other in such a way that you can make some logical conclusions. 1 to explain this.Ĭell B2 with AB (bi-value), the pivot, which connects (sees) B5 and E2Ĭell E5, the target cell to eliminate C, if any, which "sees" both B5 and E2 A Sudoku XY-Wing pattern occurs in many of the more difficult Sudoku puzzles. My own personal experience is that it is not common to find that you need this technique to solve a puzzle.There's a small mistake about Y-wing in the logic of proof: Net result: any "5" along a red line that's not in a blue line can be removed (all the 5s in the pink cells can be erased).Īpparently, some examples of this technique create a pattern that resembles the actual fish it's named after. We don't know which blue line we just know it's at a blue line. Note how the 3 cells form a 'Y' (see the red lines - it's really more like a 'V'). The result is each red line's 5 is going to be where a blue line crosses it. XY Wing involves 3 different cells each with exactly two candidates (pencil marks) that are related to each other in such a way that you can make some logical conclusions. Why is this important? Well, it isn't - unless the red lines have other 5s in them somewhere! You see, each of the three blue rows is going to have a 5, and since the possible locations are limited, each row will end up having a 5 in one of the red lines. Let me say that a different way: The blue lines only have 5s where the red lines cross. Here is the same puzzle, but with some markings added for illustration:Īs you can see, the three rows marked by the blue lines all have their possible locations for a 5 confined to the same three columns (marked by the red lines). There are three rows where all the possible 5s appear in the same three columns. Y-Wing Strategy: This is an excellent candidate eliminator (and is also known as XY-Wing). The puzzle above has a Swordfish on the number 5. It is not super complex to understand - it's just very hard to spot one.īut, in the interest of being complete, I will cover it. ![]() ![]() They are not techniques that I use myself. They are just too complicated, too hard to spot, and/or too rare to bother mentioning, quite frankly What I mean is, they are just beyond the scope of what I want this website to be. If you have already practiced and conquered all of the techniques up til now, or you're simply too. The more advanced techniques that follow are only required to solve very high level, intense puzzles. I must confess - this is probably my least favorite technique. There are a few more techniques that I do not plan to go over. You are currently armed with enough knowledge to solve 95 or more of the Sudoku puzzles currently published in newspapers, books, and magazines. Even if you know it's there, it can take some time to find. Just as the X-Wing involves two candidates in two columns or rows, the Swordfish involves three candidates in three columns or rows.
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