Grizzlybare Rated puzzle: Easy Completion time: 32:12 Used 'valid marks'
always interesting puzzles
Posted 24th Jul 2018 at 08:09
SlowBurn Best completion time: 13:04 Time on first attempt: 14:10 Used 'check puzzle' when incorrect
I might be missing something here. Can someone help? Take bottom left conner as the origin (0,0) of a normal coordinate system, then position (4,1), (4,3), (7,1) and (7,3) can have interchangeable values of "1" or "9". Is that nor true?
Posted 24th Jul 2018 at 09:53 Last edited by Elisabeth 24th Jul 2018 at 09:54
Elisabeth Daily subscriber Completion time: 28:55 Used 'show wrong moves' Used 'check puzzle' when incorrect
SlowBurn, using your coordinates, (6, 3) is a 4 and so the 1 cannot be alongside it, as 4+1 = 5 and no v so must be the 9 which fixes the others. Easy to miss!
Posted 24th Jul 2018 at 09:54
bergensbest Daily subscriber Rated puzzle: Easy Completion time: 16:45 Used 'remove' Used 'show wrong moves'
SlowBurn, if you interchange the 9s and 1s as you say then a 1 appears in the position (7,3) which is next to the 4 in position (6,3)
Posted 25th Jul 2018 at 07:13 Last edited by SlowBurn 25th Jul 2018 at 07:26
SlowBurn Best completion time: 13:04 Time on first attempt: 14:10 Used 'check puzzle' when incorrect
Thanks Elisabeth & bergensbest. Indeed I was just being blind. It seems logical that the fewer clues a puzzle contains the more challenging it will be (desirable). However, if we keep reducing the number of clues there will come a point when the solution is no longer unique (undesirable). Can someone point me to some references about this interesting subject for a casual learner please?
Posted 25th Jul 2018 at 20:49 Last edited by awesomeusername 25th Jul 2018 at 20:50
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Take bottom left conner as the origin (0,0) of a normal coordinate system, then position (4,1), (4,3), (7,1) and (7,3) can have interchangeable values of "1" or "9". Is that nor true?
Last edited by Elisabeth 24th Jul 2018 at 09:54
Last edited by SlowBurn 25th Jul 2018 at 07:26
It seems logical that the fewer clues a puzzle contains the more challenging it will be (desirable). However, if we keep reducing the number of clues there will come a point when the solution is no longer unique (undesirable). Can someone point me to some references about this interesting subject for a casual learner please?
Last edited by awesomeusername 25th Jul 2018 at 20:50
https://www.technologyreview.com/s/426554/mathematicians-solve-minimum-sudoku-problem/
EDIT: An even better resource: https://en.wikipedia.org/wiki/Mathematics_of_Sudoku
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