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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Sat May 12, 2007 9:26 pm Post subject: DB Saturday Puzzle: 12 May, 2007 |
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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
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| Posted: Mon May 14, 2007 2:14 pm Post subject: |
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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
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| Posted: Wed May 16, 2007 9:02 pm Post subject: |
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| 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
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| Posted: Wed May 16, 2007 11:20 pm Post subject: |
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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 I’m 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: 5770
Location: Rochester, NY, USA
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| Posted: Thu May 17, 2007 12:14 am Post subject: |
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| 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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