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Problem with logic

 
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g_hickley

Joined: 02 Dec 2005
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PostPosted: Wed Jan 11, 2006 10:30 am    Post subject: Problem with logic Reply with quote

I had a Sudoku game developed for my website by a third-party. A few users have described an issue where two numbers are inter-changeable creating more than one solution for the same puzzle. Below is an example - both highlighted 4 and 7 are inter-changeable. Could someone describe what problem?


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Moschopulus

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PostPosted: Wed Jan 11, 2006 11:04 am    Post subject: Reply with quote

You must have one of these four numbers as a given clue in the puzzle.
Otherwise, as you say, the puzzle has two solutions. The same is true for any set like this.

Sudoku has one solution by definition, so a puzzle with more than one solution is not a proper sudoku puzzle.
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g_hickley

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PostPosted: Wed Jan 11, 2006 11:30 am    Post subject: Reply with quote

Moschopulus wrote:
You must have one of these four numbers as a given clue in the puzzle.
Otherwise, as you say, the puzzle has two solutions. The same is true for any set like this.

Sudoku has one solution by definition, so a puzzle with more than one solution is not a proper sudoku puzzle.


Thanks for your reply. The difficulty is being able to recognise this in the algorithm and to fill in one of the four.
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Ruud
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PostPosted: Wed Jan 11, 2006 12:34 pm    Post subject: Reply with quote

Hi,

when you search this forum using the search terms: "unavoidable sets"

you'll find a lot more information on this topic. There are more complex patterns than just the 4-cell rectangle.

Ruud.
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g_hickley

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PostPosted: Sun Jan 15, 2006 10:08 am    Post subject: Another one Reply with quote

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Ruud
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PostPosted: Sun Jan 15, 2006 3:14 pm    Post subject: Reply with quote

It is worse than you think....



Ruud.
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