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 stuck in this sudoku | |
| LMI Essentials -> Solving Techniques | 159 posts • Page 3 of 7 • 1 2 3 4 5 6 7 |
debmohanty |
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     Location: India | There is an xy-wing in box4 and box7. In simple terms, it means you can rule out one of the two possibilities at R4C1. Note that you have some unmarked pencil marks at R7C3 and R8C1.  | ||
| deepika m |
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| prasanna16391 |
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2021 World Sudoku+Puzzle Convention Organizer Posts: 1809 Location: India | I was actually about to post this just before Deb posted the XY-Wing thing. Anyway, here's how I would've solved it (and something I'm able to spot more easily) - A 3 in R3C2 means it has to be in R7C3. A 2 in R3C1 means it has to be in R7C3. So both of these can't be true, so 4's in R3C2. I generally don't know names of the techniques I use, I just use them  | ||
| kishy72 |
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SM 2020 (Math) Author Posts: 419 Location: India | Dynasty sudoku from the US sudoku Team Qualification created by Wei Hwa hwang aka onigame.I have always had difficulty solving sudokus with a puzzle element attached to them .I find these kind of sudokus to be sort of a 'speed breaker' since they greatly reduce my solving pace.....So where is the continuation in here?!(Rules : 1-7 and 2 shaded cells in each row,column and Box.Shaded cells don't touch orthogonally.White cells have to be connected)  Edited by kishy72 2014-05-13 8:19 PM | ||
| swaroop2011 |
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PR 2020 (Shading and Loops) Author Posts: 668 Location: India | |||
| kishy72 |
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SM 2020 (Math) Author Posts: 419 Location: India | Hiii Swaroop!Thanks a lot!Pretty sound reasoning indeed!But don't you think that the deduction is a bit too lengthy for comfort and borders a bit more on guess work.I doubt whether someone could visualize that far without putting pen to paper.Well a few maybe?!Surely there must be some cutthroat logic from where I got stuck to proceed further. To illustrate my point take a look at this Triomino sudoku from the Japanese Grand Prix round. Rules: Place a digit from 1 to 6 into each empty cell or blacken the cell so that each digit appears exactly once in every row, column, and outlined 3x3 region along with three black cells. Each black cell should be part of an orthogonally connected group of three blackened cells (a triomino). No two triominoes can share an edge. As I see ,you can proceed further by taking a guess ,lets say at R4C4 assuming it to be a shaded cell which leads to the following ---->1 at R4C9,1 at R6C6----->Shaded cells at R5C9,R6C9,R6C8---->6 at R6C7---> shaded cell at R8C7--->2 in R8C6(you can't have a shaded cell because if you do you won't get 3 shaded cells in Box 9 (which are part of a triomino))--->2 in R5C4,5 in R5C5 --->Shaded cells in R1C6,R7C6 and R9C6(only cells in that column)---->shaded cells in R9C5 and R9C4(to get a triomino) and at last a contradiction since you get 4 shaded cells in Box 8.Phew!So you can't have a shaded cell at R4C4 and you proceed beyond after that. But do you think there is a better way without going the earlier path that I stated.There is a much stronger contination indeed!Look at cells R7C1 and R7C2 .These cells must contain atleast one shaded cell.So there cannot be a shaded cell in R9C2 because if there is, then you would have 4 shaded cells in Box 7 which violates the rule.So R9C2 must be a number and cannot be anything except a 5 and from where the sudoku proceeds like knife through butter!!This is where I feel ,the top solvers differentiate themselves from the rest.It was not before spending a lot of time that I managed to get a 5 at R9C2.So it is something like this that I would be mighty interested to know in the earlier Dynasty sudoku. ----Kishore----  Edited by kishy72 2014-05-15 9:00 PM | ||
| swaroop2011 |
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PR 2020 (Shading and Loops) Author Posts: 668 Location: India | |||
| rakesh_rai |
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Mean Minis (2020) Author Posts: 774 Location: India | |||
| swaroop2011 |
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PR 2020 (Shading and Loops) Author Posts: 668 Location: India | |||
| ka_bharath |
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| Could you please help me in proceeding with this 6x6 sudoku. The numbers in black are givens and the ones in green is what I have entered. I am unable to proceed further. Thanks, Bharath  Edited by ka_bharath 2014-07-02 7:43 PM | |||
| dp_94 |
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Posts: 25 Location: India | |||
| dp_94 |
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Posts: 25 Location: India | |||
| swaroop2011 |
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PR 2020 (Shading and Loops) Author Posts: 668 Location: India | Just to correct it, I think you meant naked pair of 3,6  dp_94 - 2014-07-02 8:01 PM its quite easy observe naked pair of 3,4 at R3C6,R6C6 and naked single i.e 4 at R2C6 | ||
| dp_94 |
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Posts: 25 Location: India | |||
| ka_bharath |
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| kishy72 |
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SM 2020 (Math) Author Posts: 419 Location: India | Sudoku Surprise - What an amazing test with a great set of sudokus.One of those tests which I felt had that rare 'reunion'of sorts between sudokus and puzzles.Rather than reflecting on my performance which was sub-optimal,I thought it would be prudent to get down to brass tacks and try understanding the beautiful intricacies hidden in each puzzle. So,I came across this Secret Code sudoku which I attempted during the test and spent close to an hour!! on this single puzzle and still could not get to the solution (logically).I guessed the answer key knowing that it had to contain one of these strings 2316,2361,3216,3261 in Column 3 .Once again ,it turned out to be a lucky guess .Hence to be candid, it's only 470 points that I could muster in reality. The reason that I am posting this here is that 80% of the solvers should have reached the following stage after which they would have hit a dead-end.The Sudoku could not have become more stuck. So fellas,if someone did find that devastating piece of logic from this point which brings the curtains down on this one ,I would be glad to know. ----Kishore-----  Edited by kishy72 2014-11-26 4:40 PM | ||
| swaroop2011 |
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PR 2020 (Shading and Loops) Author Posts: 668 Location: India | |||
| swaroop2011 |
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PR 2020 (Shading and Loops) Author Posts: 668 Location: India | |||
| kishy72 |
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SM 2020 (Math) Author Posts: 419 Location: India | |||
| kishy72 |
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SM 2020 (Math) Author Posts: 419 Location: India | Hi all!!I was randomly solving some sudokus from the IB of Swiss Team Qualification round when I came across this Arrow-thermo sudoku .I fail to see a logical continuation from the following point....Can someone spot the same and share .....  Edited by kishy72 2015-06-02 6:07 PM | ||
| Yajendra |
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Posts: 18 Location: India | |||
| kishy72 |
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SM 2020 (Math) Author Posts: 419 Location: India | |||
| gaurav.kjain |
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SM 2020 (Irregular and Outside) Author Posts: 52 Location: India | |||
| swaroop2011 |
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PR 2020 (Shading and Loops) Author Posts: 668 Location: India | |||
| kishy72 |
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SM 2020 (Math) Author Posts: 419 Location: India | |||
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