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DB Saturday Puzzle: June 9, 2007

 
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keith



Joined: 19 Sep 2005
Posts: 3179
Location: near Detroit, Michigan, USA

PostPosted: Sat Jun 09, 2007 1:58 pm    Post subject: DB Saturday Puzzle: June 9, 2007 Reply with quote

Code:
Puzzle: DB0609074  ******
+-------+-------+-------+
| 3 . . | . . 1 | . . . |
| . 4 . | . 3 . | 9 . . |
| . 5 2 | . . . | 6 7 . |
+-------+-------+-------+
| 2 . . | . . 4 | . . . |
| 5 . . | 1 . 7 | . . 4 |
| . . . | 9 . . | . . 1 |
+-------+-------+-------+
| . 1 4 | . . . | 7 3 . |
| . . 7 | . 1 . | . 5 . |
| . . . | 4 . . | . . 2 |
+-------+-------+-------+
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Marty R.



Joined: 12 Feb 2006
Posts: 5166
Location: Rochester, NY, USA

PostPosted: Sat Jun 09, 2007 11:48 pm    Post subject: Reply with quote

After the basics I spotted a Type 1 on 25 which I tried not to use. Then spotted a Type 6 on 69 which I did use, which opened up another Type 1, this one on 26, which I also tried to not use. Then found a Finned X-Wing on 6 which completed the puzzle.

I'm glad to see these puzzles posted here.
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Steve R



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

PostPosted: Sun Jun 10, 2007 12:22 pm    Post subject: Reply with quote

Since George Woods’ post I have been on the lookout for two cells with the same tow candidates but not in the same house.

After elementary moves the position is:

Code:
+----------------------------------+
| 3  68  9 |   7  56  1 | 2   4 58 |
| 7   4 68 | 256   3 25 | 9   1 58 |
| 1   5  2 |   8   4  9 | 6   7  3 |
------------------------------------
| 2 689  1 |  56 568  4 | 3  69  7 |
| 5  69  3 |   1  26  7 | 8 269  4 |
| 4   7 68 |   9 268  3 | 5  26  1 |
------------------------------------
| 8   1  4 |  25   9 25 | 7   3  6 |
| 6   2  7 |   3   1  8 | 4   5  9 |
| 9   3  5 |   4   7  6 | 1   8  2 |
+----------------------------------+

Candidates (69) in r4c8 and r5c2 fit the bill.

The X-Wing in columns 3 and 4, probably that used by Marty, eliminates 6 from r4c2 and r6c5.

Code:
+----------------------------------+
| 3  68  9 |   7  56  1 | 2   4 58 |
| 7   4 68 | 256   3 25 | 9   1 58 |
| 1   5  2 |   8   4  9 | 6   7  3 |
------------------------------------
| 2  89  1 |  56 568  4 | 3  69  7 |
| 5  69  3 |   1  26  7 | 8 269  4 |
| 4   7 68 |   9  28  3 | 5  26  1 |
------------------------------------
| 8   1  4 |  25   9 25 | 7   3  6 |
| 6   2  7 |   3   1  8 | 4   5  9 |
| 9   3  5 |   4   7  6 | 1   8  2 |
+----------------------------------+

The twin cells have gained strength because they are now linked by the conjugates for 6 in the sixth row. One of the twins must contain a 9, which can therefore be eliminated from r4c2 and r5c8, and the puzzle is solved.

This W-Wing technique seems to crop up quite often; it can also be used in the very hard puzzle for today, 10 June.

Steve

PS Like Marty I enjoy these puzzles. Thanks again to Keith for posting them.
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Sun Jun 10, 2007 8:05 pm    Post subject: X-Wing? Reply with quote

I don't see the X-Wing in C34.

However, I do see a Finned Swordfish in R145 that eliminates the <6> in R6C5.

Or, simple color wrapping on 6 eliminates both of the <6>s mentioned.

I, too, love the W-Wing. It comes up often and is powerful.
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Marty R.



Joined: 12 Feb 2006
Posts: 5166
Location: Rochester, NY, USA

PostPosted: Sun Jun 10, 2007 8:31 pm    Post subject: Reply with quote

Quote:
I don't see the X-Wing in C34.


There is no X-Wing there. I can't speak for Steve, but it looks like he was referring to strong links (skyscraper) in c34 which eliminated those 6s. I solved the 69 pairs as part of a Type 6 rectangle, after which I was here:

Code:
+---------+------------+---------+
| 3 68 9  | 7   56  1  | 2 4  58 |
| 7 4  68 | 256 3   25 | 9 1  58 |
| 1 5  2  | 8   4   9  | 6 7  3  |
+---------+------------+---------+
| 2 68 1  | 56  568 4  | 3 9  7  |
| 5 9  3  | 1   26  7  | 8 26 4  |
| 4 7  68 | 9   268 3  | 5 26 1  |
+---------+------------+---------+
| 8 1  4  | 25  9   25 | 7 3  6  |
| 6 2  7  | 3   1   8  | 4 5  9  |
| 9 3  5  | 4   7   6  | 1 8  2  |
+---------+------------+---------+


The Finned X-Wing in rows 14 finished the puzzle for me.
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