crackingthecryptic
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Could Frame by Sam Cavnar-Johnson
🕑 Added 2022-06-12 20:00:16 +0000 UTCThis is a very nice classic sudoku from Sam which needs some complicated tricks (or bifurcation!) unless you spot its secret.
Have a go at the puzzle at the link below:
https://app.crackingthecryptic.com/sudoku/HM2hg3Pngf
Rules:
Normal sudoku rules apply.
And here's a video in which you can watch both Mark and Simon's solve - Mark doesn't know the trick but Simon does... :)
Enjoy!
Simon & Mark
Comments
I‘m a bit confused that you hardly use Gurth for your solve. You rather repeat the logical steps from one area in its symmetrical wing. Instead, you could just fill those cells with the partner digit they map on. So after you have all of row 9, you could just fill in row one without repeating any of the logic. Or, in other words, every cell you deduce gives you it’s partner-in-symmetry, so of course the solve should be a lot faster than Mark‘s.
Ewen McNeill
Thanks for confirming it was that video (I found the same one via searching just as your comment came in!). Watching it now, Ewen
Ewen McNeill
Possibly this video from 2019? https://m.youtube.com/watch?v=ac7Y97t2Wns Found via a description on the Sudoku Wiki: https://www.sudokuwiki.org/Gurths_Theorem Ewen
Cracking The Cryptic
Sorry Ewen, my bad. Here it is: https://www.youtube.com/watch?v=ac7Y97t2Wns
Ewen McNeill
Thanks for the intriguing bifurcation vs knowledge video. The symmetry does help. Unfortunately now I’m feeling a bit Citation Needed as Simon mentions another video proving the symmetry theorem, but there’s no link to it here or on the YouTube video description :-( Ewen
Knowing that there's a trick is very helpful!
