For PC you have a number of them with Hodoku being the foremost but I also enjoy YZF and Xsudo. When am searching for WXYZ-Wings I use highlighting searching for the RCC first then build the ALSes from there.įor coloring of candidates there’s only one mobile app that does that effectively and that’s Sudoku Joy. In practice it’s very fast to spot without highlighting. Now all you have to do is to find within the first block a cell containing Z which is “8” that see the “8s” in ALS A and B! If there’s such a cell you remove the 8 from that cell! With XYZ-Wing you’d be searching for an almost naked pair which is super easy because the form is always fixed! For instance using your example, if there’s a cell containing the candidates where X = 1 and Z = 8. It’s better to see them using ALS-XZ logic. The idea of searching for a pivot and then two pincers is not so good especially when you extend this idea into WXYZ-Wing. It’s super easy! In fact I find it very easy to spot XYZ-Wings than I do for XY-Wings! Using the highlighting tool to find XYZ-Wings is really good but honestly you can find them without highlighting. I think that would be a huge game changer.
I have not found a user interface that allows me to color the candidates like is shown in so many solutions. This makes it easier for the eyes to find cells worth considering and excluding cells with more than two values in your scans.
For example, make the background of all bi-value cells grey. Rinse and repeat.įor other structures like Y-Wings and XY-Chains, I often highlight the bi-value cells. After the board is scanned, move to the next number - 6 in this case. Now, look around close by for a cell with either 1 and 5 as candidates or 1 and 8 as candidates. Lets say there is a cell with 5 and 8 as candidates. The highlighting of the 5 makes this easy.
I then look close by for bi-value cells with a 5. Lets say the cell has 1, 5, and 8 as candidates with the 5 being highlighted. I scan the board looking for cells with three values that include the number that is highlighted. In particular, I’m focusing on the candidates in this case. This will highlight the givens, the answers, and the candidates whose value is 5. XYZ-Wings I find by going through each number and highlighting those cells. All of these assume a fairly robust user interface. Here are some thoughts that are helping me out. Here the target number is 8.I’m developing techniques to help me find Sudoku constructs. Any 5 visible to all three cells must be removed, in this case in B1. If that's a 4 then B3 and B6 become a naked pair of 5/7 each. We can reason this way: If B6 contains a 7 then B3 and A1 become a naked pair of 4/5 - and the naked pair rule applies.Ī similar logic allies to A1. In this example the candidate number is 5 and B3 is the Hinge. It follows therefore that one or other of the three cells must contain the common number and hence any extraneous cell (there can only be two of them!) that "sees" all three cells of the XYZ-Wing cannot have that number as its true value. More precisely an XYZ-Wing has three cells that contain only 3 different numbers between them, but which fall outside the confines of one row/column/box, with one of the cells (the 'apex' or 'hinge') being able to see the other two those other two having only one number in common and the apex having all three numbers as candidates.” (Perhaps it would have been better to call it the ABC-Wing strategy but we’d be swimming against the tide)īut we have to be careful about the way the three cells are aligned. The outer cells in the formation will be XZ and YZ, Z being the common number. In Example 1, above, F9 is the source cell. It gets its name from the three numbers X, Y and Z that are required in the hinge. The interesting thing about XYZ wings is that they are cell forcing chains. This extends Y-Wings which have three bi-value cells to bi-tri-bi, in other words the hinge contains three candidates, not two.
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