Sudoku Mastery: The Y Wing (or XY Wing)

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  • Опубликовано: 22 авг 2024
  • We take a look at this extremely powerful and important technique which comes up again and again in difficult puzzles.

Комментарии • 48

  • @MoniqueLusse
    @MoniqueLusse 6 лет назад +28

    Thank you so much Simon. The way you walk through the puzzles step by step really brings the strategies home for me. Teaching in context. So good. Did my first swordfish as a result of this CTC!

  • @rjustison
    @rjustison 5 лет назад +13

    I had to watch this several times to understand it. It helped me solve a difficult puzzle. Thank you.

  • @Gravi66
    @Gravi66 4 года назад +14

    Actually in the first puzzle there is another XY-Wing (after swordfish): 267: r1c2, r2c1, r2c6. It eliminates the 7s in r1c56 which immediately gives us a 7 in r2c6 and a 4 in r1c5 and the nthe whole second square.

  • @andrewedmonds9838
    @andrewedmonds9838 2 месяца назад

    Finally, I think I understand Y wings as a result of this video and managed to use them to solve a very difficult puzzle on the CTC app - very satisfying indeed! Thank you!

  • @MwambaHakunaMajuto
    @MwambaHakunaMajuto 3 года назад +13

    it seems a difficult thing to spot if you dont use full notation

  • @GaimeGuy
    @GaimeGuy 4 года назад +5

    I can apply XY Wings, 3 linked color chains, and swordfish techniques, but I have an incredible amount of difficulty spotting them myself. On Andoku 3, these techniques are intrduced in the "Hard" tier of puzzles, and I usually find myself at a point where I have... about 30 or so squares left to fill in the puzzles, and all the pencil marks filled in, and I wind up flailing blindly from any 3-cell combo of 3-4 candidates with 2 candidates per cell I can find ("Hey, there's a cell with 56 candidates, a cell with 1 5 candidates, and a cell with 16, and a cell with 1 candidates, and look, the 5 or 1 or 6 has only two candidates in this house... maybe this will work. " And then a minute later I realize it was a dead end all along and I start scanning again, hoping to stumble upon a different chain or wing that bears fruit.
    For example, in the puzzle at 7:12, my eyes immediately went towards columns 4 and 6 - the 34, 14, and 48 cells. If I were solving this puzzle myself, on my own, I probably would have started pencilling in the remaining candidates in subgrids 5 and 8, then and moved to subgrids 6 and 9.
    I guess I just have bad intuition for these things since there's a bit of a spacial component to them, rather than mere set logic. Do you have any advice on getting better at them?

  • @jakesprake
    @jakesprake 5 лет назад +9

    I've never understood swordfishes but in this example it looks like an X wing in blocks 3 and 6 with a horizontal and vertical one attached. Thanks Simon.

  • @jeffbrunton3291
    @jeffbrunton3291 4 года назад +19

    Helpful, thanks
    I call Y wings ‘bent triple’ as that helps me remember them more easily
    But I realise I have only been looking for right angle versions, whereas I should be looking for more variations / 2 in a box

  • @olima-
    @olima- Год назад +1

    There should definitely be a CtC history channel - this video looks so vintage in 2022. What a difference to nowadays.

  • @everetmason7793
    @everetmason7793 2 года назад +1

    Thanks so much! FINALLY understand the Y-wing technique.

  • @Voodoo.77
    @Voodoo.77 2 года назад +3

    I’ve worked sudoku puzzles for years. I NEVER have been able to find an XY wing. Apparently there’s something I’m not picking up on

  • @jonathanmccormick902
    @jonathanmccormick902 4 года назад +6

    Your Y-Wing in the first puzzle also eliminates the 2s in D1 and F1, forcing a 2 in D2.

  • @voljes9007
    @voljes9007 3 года назад +2

    Thank you for this lesson, it's very clear and helpful!

  • @RussellSmith-nv2je
    @RussellSmith-nv2je 5 лет назад +3

    Thank you for such a clear explanation!

  • @Cachirepublica
    @Cachirepublica 2 года назад +1

    7:10 3 cells, 2 digits each. 3 unknown digits in total . Pivot is the one that look at the other two.

    • @jand147
      @jand147 2 года назад

      That's it in a nutshell!

  • @Feenix102
    @Feenix102 3 года назад +1

    I have a question. In the last puzzle you show, there is a 4-8 pairing in column one, and a 3-4 pairing in the same square right, square 7? In column 2? So, could the 4-8 and 3-4 pairing from square 7, columns 1 and 2, be in a Y wing with the 3-8 pairing at the top of column 2? In other words, could the y wing be in columns 1 and 2 or does it have to be in columns 2 and 3, and if so, why? Cheers. :o)

    • @MrMarcLaflamme
      @MrMarcLaflamme 2 года назад

      Yeah I was going to ask the same thing.

  • @rwprime1
    @rwprime1 3 года назад +3

    Before you even start, in column 6 / row 2 how did you exclude the 2? Column 7 / row 2 how did you exclude the 4? And Column 7 / row 4 how did you exclude the 4? I just don't see it.

    • @kaybrown8885
      @kaybrown8885 3 года назад

      I'm at this same point. I don't see how to exclude that 2 or 4 either.

    • @mirish25m
      @mirish25m 3 года назад +1

      This question is actually why I'm reading the comments. I also have those exact three numbers listed as options

    •  3 года назад

      Same, exact three options are here and I don't see the reasoning to take them out

    • @rwprime1
      @rwprime1 3 года назад

      I just revisited this by running it through Andrew Stuart's online solver (using the "Take Step" button) and the two 4s I mentioned above were eliminated by Swordfish. So there you go. Try Andrew's solver and the boxes (pattern) will appear at the swordfish 'step'.

    • @mirish25m
      @mirish25m 3 года назад

      @@rwprime1 I eventually found the swordfish on my own as well, but still don't know how the 2 was eliminated from r2c6 at this point

  • @lukejuras8024
    @lukejuras8024 Год назад

    Can you eliminate the 7 in row 1, column 6, if you use the 2-6 as the pivot, and the 2-7 and 6-7 (found in box 2) as pincers? I paused the video and that was the xy wing I found, so I was a little confused that there was another xy wing as your example!

  • @dvoorganisation459
    @dvoorganisation459 5 лет назад

    Thank you Sir ji

  • @MKIdefix92
    @MKIdefix92 2 года назад

    I tried my hands on the last puzzel, but I cant solve it. I get stuck with thousend pencilmarks and only 7 singels entered so far. Its been 2 weeks..... I think I need help. I tried it various times with either 3 or 8 in r1c2 and it just seem like it doesn't work. I feel so stupid and frustrated

  • @dvoorganisation459
    @dvoorganisation459 5 лет назад

    Thank you Sir

  • @veryfrostyjack3067
    @veryfrostyjack3067 5 месяцев назад

    9:00 COuldnt the right cell be the pivot? 3 and 4 can see all others

    • @abhayraj4189
      @abhayraj4189 8 дней назад

      If u mean r8c4, No because it is only seeing one of required cell

  • @sylviacarlson3561
    @sylviacarlson3561 2 года назад

    Does every puzzle have an XY wing? I've gone thru a hard puzzle and only kept the cells that have two numbers and I do not see an XY wing.

  • @ChongFrisbee
    @ChongFrisbee 4 года назад

    Wait. I'm having a hard time understanding why the 4 needed to be eliminated. When I look at the green triple, it seems that since 2 can't be in column 5, then there has to be a 2 in one of the other cells in the triple. And any of those 2 positioned would eliminate the 2 from the cell in columns 1
    Is my reasoning mistaken or did Simon simply missed this reasoning?

    • @ChongFrisbee
      @ChongFrisbee 4 года назад

      Oh, I wrote in too soon. In the following example, the type of reasoning I described doesn't work, so there is a good reason to go about it that way in the video

  • @SenfSenferson
    @SenfSenferson 2 года назад

    My Brain hurts ^^

  • @fabianowiti5250
    @fabianowiti5250 2 года назад

    I feed dumb because i just don't get the logic... I thought i was good at soduku.

  • @rlsdw745
    @rlsdw745 4 года назад +1

    dont use green

  • @Magikookeven
    @Magikookeven 5 лет назад

    What music in the intro?

  • @JH-ub8nz
    @JH-ub8nz 2 года назад

    Is anyone else here in their 20s?

  • @nup418jekhicmem5
    @nup418jekhicmem5 3 года назад

    The voracious shrine partially whine because need complimentarily whip about a agonizing lawyer. wooden, hapless creditor

  • @nicholasflamegun3883
    @nicholasflamegun3883 5 лет назад +1

    Can't hear a bloody word he's saying

    • @louibeans
      @louibeans 5 лет назад +9

      Maybe check your ears then