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DB Saturday Puzle - September 9, 2006

 
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keith



Joined: 19 Sep 2005
Posts: 3173
Location: near Detroit, Michigan, USA

PostPosted: Sat Sep 09, 2006 3:19 pm    Post subject: DB Saturday Puzle - September 9, 2006 Reply with quote

I have yet to look at it:
Code:
Puzzle: DB090906  ******
+-------+-------+-------+
| 3 . . | 8 . . | . . . |
| . . 9 | . 4 . | 1 . . |
| . . 5 | 1 3 . | . . 8 |
+-------+-------+-------+
| 6 5 1 | 2 . . | . . . |
| . . . | . . . | . . . |
| . . . | . . 1 | 8 6 2 |
+-------+-------+-------+
| 8 . . | . 1 9 | 5 . . |
| . . 6 | . 8 . | 4 . . |
| . . . | . . 5 | . . 3 |
+-------+-------+-------+

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5160
Location: Rochester, NY, USA

PostPosted: Sat Sep 09, 2006 6:32 pm    Post subject: Reply with quote

After the basic stuff, I reached the posted position. I wanted to solve it without chains, but couldn't see anything there. So I thought r2c1 had good potential for a chain and a "2" in that cell solves the puzzle.

Code:
----------------------------------------
|3   1   247 |8   9   267 |26  457 45  |
|27  8   9   |5   4   267 |1   3   67  |
|247 6   5   |1   3   27  |29  479 8   |
----------------------------------------
|6   5   1   |2   7   8   |3   49  49  |
|29  23  8   |39  6   4   |7   15  15  |
|479 347 347 |39  5   1   |8   6   2   |
----------------------------------------
|8   234 234 |46  1   9   |5   27  67  |
|5   29  6   |7   8   3   |4   129 19  |
|1   479 47  |46  2   5   |69  8   3   |
----------------------------------------
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David Bryant



Joined: 29 Jul 2005
Posts: 559
Location: Denver, Colorado

PostPosted: Sat Sep 09, 2006 10:19 pm    Post subject: XY-Wing alternative Reply with quote

Alternatively, the XY-Wing from r2c9 lets you eliminate the "2" at r1c3, and that creates the {4, 7} pair in column 3 ... dcb
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Marty R.



Joined: 12 Feb 2006
Posts: 5160
Location: Rochester, NY, USA

PostPosted: Sun Sep 10, 2006 12:32 am    Post subject: Re: XY-Wing alternative Reply with quote

David Bryant wrote:
Alternatively, the XY-Wing from r2c9 lets you eliminate the "2" at r1c3, and that creates the {4, 7} pair in column 3 ... dcb

As I sit here kicking myself, I wonder why I missed that, since I consciously searched for XY-Wings. Thanks David.
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keith



Joined: 19 Sep 2005
Posts: 3173
Location: near Detroit, Michigan, USA

PostPosted: Sun Sep 10, 2006 3:53 am    Post subject: A possible UR? Reply with quote

I have been staring at the possible UR on <27> in R23C16.

But, I think, we are one strong link short.

Keith
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TKiel



Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI

PostPosted: Sun Sep 10, 2006 1:43 pm    Post subject: Reply with quote

David Bryant wrote:
Alternatively, the XY-Wing from r2c9 lets you eliminate the "2" at r1c3, and that creates the {4, 7} pair in column 3


I also used the XY-wing but completely missed the creation of the naked pair in column 3. Fortunately, a box/line interaction (locked candidates) is created in box 1, which allows exclusion of other 2's in column 1 and placement of 2 in r5c2. The end result is about the same as if I had used the naked pair, but with a few additional steps.

That's one thing that I like about these puzzles. It seems that quite often the key step doesn't directly solve the puzzle (i.e. turn everything else into singles) but it does directly lead to the solution.
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