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DB Saturday Puzzle: 12 May, 2007

 
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keith



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

PostPosted: Sat May 12, 2007 9:26 pm    Post subject: DB Saturday Puzzle: 12 May, 2007 Reply with quote

I haven't posted one of these for a while. Because they have required chains. I found this one relatively easy.
Code:
Puzzle: DB051207 ******
+-------+-------+-------+
| . 3 1 | . . . | . . 8 |
| . . 9 | . 8 1 | 6 3 . |
| . . 8 | 2 5 . | . . . |
+-------+-------+-------+
| . . . | 3 . . | . 4 . |
| 8 . 3 | . . . | 5 . 2 |
| . 9 . | . . 8 | . . . |
+-------+-------+-------+
| . . . | . 7 6 | 9 . . |
| . 6 7 | 9 2 . | 3 . . |
| 9 . . | . . . | 2 7 . |
+-------+-------+-------+

Enjoy!

Keith
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Steve R



Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England

PostPosted: Mon May 14, 2007 2:14 pm    Post subject: Reply with quote

Thanks for the puzzle, Keith.

I paused at this point:

Code:

+----------------------+
5 3 1 . . . . 2 8
. . 9 . 8 1 6 3 5
6 . 8 2 5 3 . . .
------------------------
. 5 6 3 . 2 8 4 .
8 . 3 . . . 5 . 2
. 9 . 5 . 8 . . 3
------------------------
3 . . . 7 6 9 5 .
. 6 7 9 2 5 3 8 .
9 . 5 . 3 4 2 7 6
+----------------------+

The missing candidates in box 7 and row 9 are (18) so 8 can be eliminated from r7c2 if you are prepared to assume there is a unique solution. This places 8 in r9c2 and solves the puzzle.

Some other pairs are almost as obvious:
Code:

+-------------------------+
  5  3  1 . . . . 2 8
  .  .  9 . 8 1 6 3 5
  6  .  8 2 5 3 . . .
---------------------------
  .  5  6 3 . 2 8 4 .
  8 14  3 . . . 5 . 2
  .  9 24 5 . 8 . . 3
---------------------------
  3  . 24 . 7 6 9 5 .
14  6  7 9 2 5 3 8 .
  9  .  5 . 3 4 2 7 6
+-------------------------+

The sequence (14) (24) (24) (14) is not properly speaking an example of remote pairs but it is just as easy to spot and has exactly the same effect: 1 may be eliminated from any common associate of r5c2 and r8c1. Here the result is again to place 8 in r9c2.

This is indeed a chain. Still, if other DB chains are as straightforward as this, I for one should be keen to see a few more examples. Thanks again.

Steve
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David



Joined: 02 Jun 2006
Posts: 58
Location: Bedford, UK

PostPosted: Wed May 16, 2007 9:02 pm    Post subject: Reply with quote

How about using the type 4 UR at r7c2,4 and r9c2,4 ?
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Steve R



Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England

PostPosted: Wed May 16, 2007 11:20 pm    Post subject: Reply with quote

Is it type 4?

As explained immediately below the first grid in my post I simply eliminated 1 and 8 from r7c2 on the grounds that (18) were the only candidates for the other three corners of the UR.

I thought this was type one. However Im not good on type numbers. Also, as this move reduced the puzzle to singles, I did not look further. Perhaps you have something different in mind.

Steve
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Marty R.



Joined: 12 Feb 2006
Posts: 5124
Location: Rochester, NY, USA

PostPosted: Thu May 17, 2007 12:14 am    Post subject: Reply with quote

I agree with Keith that this one was easy. I also recall a Type 1 rectangle on 18 that was all that was needed to finish it off.
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