Naked Quad Example

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Naked Quad Example

Postby civiliza » Sat May 14, 2011 6:27 pm

I'm sure it's no big deal to experienced Sudoku Generators / Compilers, but according to Sudoku Explainer my Puzzle Generator just randomly created it's first puzzle with a Naked Quad.

For anyone looking to test their ability to solve Naked Quads, try the following:

Code: Select all
000000000
000031600
000008090
019800050
600070030
200000700
100020080
860059200
000100045
civiliza
 
Posts: 64
Joined: 25 October 2010

Re: Naked Quad Example

Postby eleven » Tue May 17, 2011 1:22 pm

Nice, puzzle, hard on paper.

For me its easier to see the hidden quad (like the hidden pair 16 before), which still does not give you a number directly ...
Code: Select all
 +-------+-------+-------+
 | x x 16| . 9 . | x . x |
 | . . . |*5*3 1 | 6 . . |
 | . . 16| .*4*8 | . 9 . |
 +-------+-------+-------+
 | 7 1 9 | 8 6 3 | .*5 2 |
 | 6 . . | . 7 . | .*3 . |
 | 2 . . | . 1 . | 7 6 . |
 +-------+-------+-------+
 | 1 . . | . 2 . | .*8 6 |
 | 8 6 . | . 5 9 | 2 . . |
 | . . . | 1 8 6 | .*4 5 |
 +-------+-------+-------+
eleven
 
Posts: 1559
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Re: Naked Quad Example

Postby dyitto » Sat May 28, 2011 8:08 am

What would be the next move from here?
Code: Select all
*--------------------------------------------------------*
|  345    38    16 |  267     9    27 |   58   127   348 |
|   49    89    27 |    5     3     1 |    6    27    48 |
|   35    27    16 |  267     4     8 |   15     9   137 |
|------------------+------------------+------------------|
|    7     1     9 |    8     6     3 |    4     5     2 |
|    6    45   458 |  249     7   245 |   18     3   189 |
|    2   345  3458 |   49     1    45 |    7     6    89 |
|------------------+------------------+------------------|
|    1  3459   345 |  347     2    47 |   39     8     6 |
|    8     6    34 |   34     5     9 |    2    17    17 |
|   39    27    27 |    1     8     6 |   39     4     5 |
*--------------------------------------------------------*
evert on the crashed forum
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Location: Amsterdam

Re: Naked Quad Example

Postby RW » Sat May 28, 2011 8:41 am

dyitto wrote:What would be the next move from here?

I think a XY-wing in r13 should take care of that.

But there's also a quite interesting BUG-lite:
Code: Select all
*--------------------------------------------------------*
|  345    38   *16 | *267     9    27 |   58  *127   348 |
|   49    89   *27 |    5     3     1 |    6   *27    48 |
|   35   *27   *16 | *267     4     8 |   15     9  *17+3|
|------------------+------------------+------------------|
|    7     1     9 |    8     6     3 |    4     5     2 |
|    6    45   458 |  249     7   245 |   18     3   189 |
|    2   345  3458 |   49     1    45 |    7     6    89 |
|------------------+------------------+------------------|
|    1  3459   345 |  347     2    47 |   39     8     6 |
|    8     6    34 |   34     5     9 |    2   *17   *17 |
|   39   *27   *27 |    1     8     6 |   39     4     5 |
*--------------------------------------------------------*

that would suggest r3c9=3.

RW
RW
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Posts: 1000
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Re: Naked Quad Example

Postby aran » Wed Jun 01, 2011 4:07 pm

Code: Select all
*--------------------------------------------------------*
|  345    38    16 |  267     9    27 |   58   127   348 |
|   49    89    27 |    5     3     1 |    6    27    48 |
|   35    27    16 |  267     4     8 |   15     9   137 |
|------------------+------------------+------------------|
|    7     1     9 |    8     6     3 |    4     5     2 |
|    6    45   458 |  249     7   245 |   18     3   189 |
|    2   345  3458 |   49     1    45 |    7     6    89 |
|------------------+------------------+------------------|
|    1  3459   345 |  347     2    47 |   39     8     6 |
|    8     6    34 |   34     5     9 |    2    17    17 |
|   39    27    27 |    1     8     6 |   39     4     5 |
*--------------------------------------------------------*

Another possibility : avoiding the deadly pattern 45 in r56c26 leads quickly to r5c6=2
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Posts: 334
Joined: 02 March 2007

Re: Naked Quad Example

Postby civiliza » Mon Jul 11, 2011 12:05 am

eleven wrote:For me its easier to see the hidden quad ...


Strange you should mention that:
Code: Select all
000000000
679000008
010006209
500960001
200850000
000000000
050200306
008040705
706005090
civiliza
 
Posts: 64
Joined: 25 October 2010


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