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DB Saturday Puzzle - August 26, 2006

 
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Sat Aug 26, 2006 1:18 pm    Post subject: DB Saturday Puzzle - August 26, 2006 Reply with quote

I have not yet looked at this one ...

Keith
Code:
Puzzle: DB082606  ******
+-------+-------+-------+
| . 6 8 | . . . | 1 9 . |
| 2 . . | . . 3 | . . 5 |
| . . . | . 9 . | . 2 . |
+-------+-------+-------+
| . . 5 | 8 4 . | 9 . 7 |
| . . . | 7 . 5 | . . . |
| 1 . 3 | . 6 9 | 5 . . |
+-------+-------+-------+
| . 3 . | . 1 . | . . . |
| 7 . . | 9 . . | . . 1 |
| . 1 2 | . . . | 4 5 . |
+-------+-------+-------+
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Sat Aug 26, 2006 4:01 pm    Post subject: Reply with quote

This one moved along pretty quickly. After the basic stuff, a Type 1 rectangle opened up the rest of the puzzle. There may have been some X-Wings, XY-Wings and other stuff, but I didn't reach a point where it was necessary to look for them.
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Sat Aug 26, 2006 4:15 pm    Post subject: Two UR's Reply with quote

You get here:
Code:
+----------------+----------------+----------------+
| 34   6    8    | 5    2    7    | 1    9    34   |
| 2    9    17   | 146  8    3    | 67   467  5    |
| 34   5    17   | 146  9    46   | 678  2    3468 |
+----------------+----------------+----------------+
| 6    2    5    | 8    4    1    | 9    3    7    |
| 89   48   49   | 7    3    5    | 26   1    26   |
| 1    7    3    | 2    6    9    | 5    48   48   |
+----------------+----------------+----------------+
| 5    3    69   | 46   1    468  | 2678 678  2689 |
| 7    48   46   | 9    5    2    | 3    68   1    |
| 89   1    2    | 3    7    68   | 4    5    689  |
+----------------+----------------+----------------+

Ther are two Unique Rectangles: A Type 1 in R13C19, and a Type 4 in R57C79. The first one solves the puzzle.

Otherwise, there is an XY-wing on <689> rooted in R9C1. It also solves the puzzle.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Sat Aug 26, 2006 9:12 pm    Post subject: Reply with quote

I used that Type 1 on 34 to solve the puzzle. Have no idea if I would have spotted the 689 XY-Wing.
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Sat Aug 26, 2006 10:43 pm    Post subject: Me neither Reply with quote

Marty,

While solving the puzzle by hand, I found the first <34> UR pretty early. The rest was easy.

I used my software to find the other UR and the XY-wing. I always like to look at the question: If you do not use a UR, how else would you solve it?

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Sun Aug 27, 2006 3:39 am    Post subject: Re: Me neither Reply with quote

keith wrote:
Marty,

While solving the puzzle by hand, I found the first <34> UR pretty early. The rest was easy.

I used my software to find the other UR and the XY-wing. I always like to look at the question: If you do not use a UR, how else would you solve it?

Keith

I'm strictly a paper-and-pencil guy and usually don't look for alternate solutions. I've always taken the path of least resistance to the solution; if I see something, I use it. The one thing that's changed is that I am trying to reduce my dependence on chains, so I don't go to them as quickly as I used to.
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