Explanation and demonstration of the very POWERFUL Sudoku Solving Technique known as the W-Wing. Explained in terms of an AIC of 5 Links between a Conjugate Pair and two identical Bi-Value Cells. Includes numerous diagrams and examples.
Simply BRILLIANT. A lot of fun once one gets the hang of it. But needs a trained eye to spot them in a real puzzle. Nothing new! Thanks looking forward to #26!
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You refer to them as ( W Wing) pincers cells, I call them intersecting pairs. Example, 12:17 the 92 pairs intersect on row 3, column 6 leaving only a 5
Without the two 9's in Block 6, the (9-2) pairs will not have any effect on R3C6, all by themselves. The eliminations are only possible by virtue of the Chain.
Thank you for making this video. There were many good examples here that I probably would not have noticed in puzzles whatsoever until this video. My enjoy sudoku app teaches a 'type D' variant and ONLY the type D variant and not a true W wing. After watching the video I hope to include other forms of W wing in my solving path. Thanks for this lesson. You could argue that the type D variant my app teaches is not actually a W wing as it does not necessarily involve a conjugate pair, but it is still produces valid eliminations. I feel the type D is very common and also easy to spot (and can provide 6 eliminations). This case only applies when the 2 BVC's lie in the same chute. Then looking at the 3 cells in the same chute that do not see any of the BVC cells, if they do not contain one of the BVC candidates (lets call said candidate A) then you can eliminate candidate B from the 6 cells that do see both of the BVC's. Specifically these 3 cells I'm talking about, are the cells in the intersection between 3rd block and the 3rd row / column in that chute (where both this block and this row / column do not contain any of the BVC cells). Why can you do this? If you look at the 3rd block in the chute (not containing any of the BVC cells), candidate A either appear in the 3 cells that see the 1st BVC (ie in the intersection between the 3rd block and 1st row) or appear the other 3 cells that see the 2nd BVC (in the intersection between the 3rd block and 2nd row). Similarly to how a conjugate pair works, this forces candidate B into 1 of the BVC cells meaning B can be eliminated from the 6 cells that see both of the BVC cells. If this explanation I gave is unclear which it probably is because it's purely text based, then I can email you a link to enjoy sudoku's external page for it (enjoy sudoku has pages externally to the app mirrored from sudopedia on top of its in app tutorials). This type is very easy to spot once you see both BVC's. Just check the 3 cells I've talked about, and if they are missing one or both candidates of the BVC's then bingo. If this is not the case you don't have a type D but you may still have a W wing like the types shown in the video (where the conjugate pair lies outside the chute). This type could possibly feature as an Adjunct video to this given it's not technically a W wing but has proven VERY helpful to me in puzzle solving. As a result of the type D method I find it far easier to look for BVCs first as the type D variation can occur without a conjugate pair. Then if the BVCs aren't suited for a type D or lie in 2 separate chutes then I can try and hook it up to a conjugate pair. If there's still no luck I could get creative and hook it up to an X chain (though probably waste large amounts of time doing so).
I just looked at Enjoy Sudoku's explanation of their W-Wing Type D. I have never heard of this before. What they are saying, as I think you understand, is that instead of a pure Conjugate Pair as the "Pivot," they are using a "Group Node" Conjugate Pair. If you can see this Pattern, then that's great. It IS valid, and it does work. But to me, it is a special case and a variation of the larger W-Wing concept, and does not fall under the formal definition.
Sudoku Swami It is a limitation of the W wing which is why your video explaning the general case of W wing is helpful. And yes you can think of it using conjugate pairs of group nodes. The vast majority of the time (if the 3rd house does not contain candidate A) then you will have an actual conjugate pair of A somewhere and no need to employ this technique. However I still find it a useful short cut because if I check these 3 cells and they don't have candidate A then I can look no further for conjugate pairs which is a huge timesaver. When the type D rule doesn't apply, then I will try and look for the general case as you taught in the video.
I just go to Enjoy Sudoku and I find there are 5 types of W-Wing. Swami's W-Wing fallls into Type A and Type C. Type D is just using the empty-rectangle concept as an alternative to strong link conjugate pair as introduced by Swami.
I am wondering if there are puzzles where the same chain can be used as a w wing and a turbot fish. At 17:42 in the video, you show a w wing using cells at row 1 , column 3 and 7 and cells at row 5 columns 2 and 5. This is also similar to a turbot fish but not quite.
Those four Cells actually contain a Skyscraper on Candidate 1, but there are no possible eliminations as a result of it. The answer to your question, is that yes, it is possible to have two Chains available at the same time, using the same Cells. But all you need to do, is execute the first one you see. You can NEVER make the situation worse, by solving one before the other. Or I should rather say, that solving one before the other will never be less advantageous. It will all work out, in the end. :-))
Sir, In Time - 15:43 Since {1,4} are appearing in all cells (Coloured) can we eliminate 4 instead of 1 that sees both end points? or can we remove both(1 & 4) that sees both the end points.
Your question must contain some errors with regard to rows and columns, because it doesn't make any sense. Please check and re-write your question correctly, and I will try to answer it.
Your described Cells DO NOT form a W-Wing. The Endpoints of a W-Wing must lie in Identical Bi-Value Cells, and they must be connected by a Conjugate Pair on the OTHER Candidate. Please watch the Video again.
16:01 If R2C3 is 1, R1C1 and R2rC8 will be 4 Then R4C1 & R4C8 4 will be eliminated And this still right. I think W-wings not effect to this case Could you please explain more how can you eliminate 1 in R2C3 , thank you
Because of the AIC connecting the 1 in R1C1 to the 1 in R2C8, we know that at least ONE of those two 1's must be True. Therefore any OTHER Candidate 1 that can see BOTH Endpoints of the Chain MUST be False. Therefore the 1 in R2C3 is False, and likewise, the 1 in R1C7 is False. If you do not understand this, please go back and watch Videos #3, and #4. Good luck.
Type D is a special case for W-Wings. I have only seen it covered (or even mentioned) in the Enjoy Sudoku App. If you want to learn about it, I suggest you look there. I only cover the Standard Type. Good luck!
@@SudokuSwami That explains it. I just ran into type D on the Enjoy Sudoku app and was struggling to work out the strong-weak links. Their explanation for w-wings left me unable to replicate the logic. Yours works like magic! Thank you so much for this whole series. What a lot of planning and works for you, kind sir.
Yes, I plan to cover them in my Advanced Series. WXYZ-Wing configurations are not as common as other types of Wings, but I still think it's worth studying how they work. Please be patient. Thank you.
Hello Fahad, I'm so sorry, but I do not understand your question as stated. Can you please try to be more clear in what you are asking? And I will try my best to answer. :-) Thanks.
I am very sorry, but I still do not understand what you are asking. Calculated from what? Calculated how? Sudoku strategies and solving techniques are not calculations. They are logical relationships and applications.
