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Aug 22 DB

 
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Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS

PostPosted: Sat Aug 22, 2009 1:28 pm    Post subject: Aug 22 DB Reply with quote

The August 22 DB offers x-wings, coloring, etc. but you need only this one step.

Solution: 23 W-wing

Earl

Code:

+-------+-------+-------+
| . . . | 7 . . | . 9 4 |
| 7 . 1 | 6 . . | . . . |
| . . 8 | . 1 4 | . . 7 |
+-------+-------+-------+
| 1 7 6 | 8 . . | . . . |
| . . . | . 5 . | . . . |
| . . . | . . 6 | 8 7 1 |
+-------+-------+-------+
| 6 . . | 9 7 . | 4 . . |
| . . . | . . 5 | 9 . 8 |
| 5 3 . | . . 1 | . . . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Sat Aug 22, 2009 5:06 pm    Post subject: Reply with quote

After basics:
Code:
+-------------+-------------+-------------+
| 23  6   5   | 7   23  8   | 1   9   4   |
| 7   4   1   | 6   239 29  | 5   8   23  |
| 239 29  8   | 5   1   4   |236* 26* 7   |
+-------------+-------------+-------------+
| 1   7   6   | 8   4   29  | 23  5   239 |
| 8   29  3   | 1   5   7   |-26* 4  -269*|
| 29  5   4   | 3   29  6   | 8   7   1   |
+-------------+-------------+-------------+
| 6   8   2   | 9   7   3   | 4   1   5   |
| 4   1   7   | 2   6   5   | 9   3   8   |
| 5   3   9   | 4   8   1   | 7   26* 26* |
+-------------+-------------+-------------+

There is a possible DP <26> in R359.

Either R3C7 is <3> or R5C9 is <9>. Either way, R5C79 are not <2>, and the puzzle is solved.

Keith Cool
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dlnichols



Joined: 22 Aug 2009
Posts: 2

PostPosted: Sat Aug 22, 2009 5:14 pm    Post subject: August 22 ???? Reply with quote

It appears to be a guess. Do you have a solution?
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dlnichols



Joined: 22 Aug 2009
Posts: 2

PostPosted: Sat Aug 22, 2009 5:30 pm    Post subject: what is a W-wing? Reply with quote

What is a W-wing?
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sat Aug 22, 2009 6:23 pm    Post subject: Re: what is a W-wing? Reply with quote

dlnichols wrote:
What is a W-wing?

http://www.dailysudoku.co.uk/sudoku/forums/viewtopic.php?t=2008

that is a link to a thread in this forum. in that thread are other links to threads that discuss the w-wing and its different forms.
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Sat Aug 22, 2009 9:59 pm    Post subject: Reply with quote

dl,

Welcome to the forum!

If you are ready to try W-wings, please read this thread:

http://www.dailysudoku.com/sudoku/forums/viewtopic.php?t=2143

You will learn about general Remote Pairs, M-wings, etc.

The basic idea is that if you have two unconnected cells with the same two candidates, how can you connect them?

Best wishes,

Keith
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Sat Aug 22, 2009 10:20 pm    Post subject: Reply with quote

dl,

After basics:

Code:
+-------------+-------------+-------------+
| 23  6   5   | 7   23  8   | 1   9   4   |
| 7   4   1   | 6   239 29# | 5   8   23@ |
| 239 29  8   | 5   1   4   | 236 26  7   |
+-------------+-------------+-------------+
| 1   7   6   | 8   4   29# | 23@ 5  2-39 |
| 8   29  3   | 1   5   7   | 26  4   269 |
| 29  5   4   | 3   29  6   | 8   7   1   |
+-------------+-------------+-------------+
| 6   8   2   | 9   7   3   | 4   1   5   |
| 4   1   7   | 2   6   5   | 9   3   8   |
| 5   3   9   | 4   8   1   | 7   26  26  |
+-------------+-------------+-------------+

Notice the pair <23> labeled @. How can they be connected? Well, there is a strong link on <2> labeled #.

The logic is: One of the # cells must be <2>, so one of the @ cells must be <3>. So, R4C9 cannot be <3>, solving the puzzle with only further basic moves.

Best wishes,

Keith
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Sat Aug 22, 2009 10:30 pm    Post subject: Re: August 22 ???? Reply with quote

dlnichols wrote:
It appears to be a guess. Do you have a solution?


dl,

If you mean my previous message on a Deadly Pattern, this is not a guess:

If all of the cells marked * have only possibilities <26>, the puzzle does not have a unique solution. You can exchange 2 for 6 in any of the * cells, and still have a valid solution.

To break up the <26> Deadly Pattern,
Quote:

Either R3C7 is <3> or R5C9 is <9>. Either way, R5C79 are not <2>, and the puzzle is solved.


Is this good stuff, or not! Very Happy

Keith
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strmckr



Joined: 18 Aug 2009
Posts: 64

PostPosted: Sun Aug 23, 2009 7:20 am    Post subject: Reply with quote

Code:
 *--------------------------------------------------*
 | 23   6    5    | 7    23   8    | 1    9    4    |
 | 7    4    1    | 6    39   29   | 5    8    23   |
 | 39   29@  8    | 5    1    4    | 23-6 26@  7    |
 |----------------+----------------+----------------|
 | 1    7    6    | 8    4    29   | 23   5    239  |
 | 8    29@  3    | 1    5    7    | 26@  4    69   |
 | 29   5    4    | 3    29   6    | 8    7    1    |
 |----------------+----------------+----------------|
 | 6    8    2    | 9    7    3    | 4    1    5    |
 | 4    1    7    | 2    6    5    | 9    3    8    |
 | 5    3    9    | 4    8    1    | 7    26   26   |
 *--------------------------------------------------*



W-Wing: 6/2 in r3c8,r5c7 connected by 2 in r35c2 => r3c7<>6
also works...
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