Unsolvable puzzle - Why does this happen?

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Unsolvable puzzle - Why does this happen?

Postby Madolite » Mon Nov 05, 2018 7:25 pm

Sometimes, when I "solve" a Sudoku puzzle, I end up with interchangeable pairs that can't be definitively resolved (or so it seems). Is this a design flaw, or is there something on my board that I've missed? The puzzle was found in a Sudoku book, it's "Black Belt" difficulty. The issue below is trying to see the definitive location of 9 and 6 on c7, c8 and c9:

As far as I can tell, either placement is fine and will solve the puzzle. :?
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Re: Unsolvable puzzle - Why does this happen?

Postby champagne » Mon Nov 05, 2018 7:41 pm

One could say that this is a puzzle with multiple solutions,
on the other side, I see 2 times the digit 9 in column 4 and this is not possible
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Re: Unsolvable puzzle - Why does this happen?

Postby 999_Springs » Mon Nov 05, 2018 8:02 pm

it looks like you messed up the puzzle right at the end, like champagne said there are 2 nines in column 4 and 2 ones in column 6. But this is very easy to fix, all you need to do is erase these 3 cells
Hidden Text: Show
r1c4
r1c8
r3c6

and the puzzle solves itself from there
Once upon a time I was a teenager who was active on here 2007-2011
ocean and eleven should have paired up to make a sudoku-solving duo called Ocean's Eleven
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Re: Unsolvable puzzle - Why does this happen?

Postby Madolite » Mon Nov 05, 2018 8:09 pm

Ah yeah I see it now, so after I fix it and put 1 into r3c8 it'll resolve. thanks guys! :D
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Re: Unsolvable puzzle - Why does this happen?

Postby SteveG48 » Tue Nov 06, 2018 6:56 pm

But to answer your other question, if the puzzle did have multiple solutions, then this would be considered a design flaw in the puzzle.
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