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May 19, 2009 VH

 
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crunched



Joined: 05 Feb 2008
Posts: 168

PostPosted: Mon May 18, 2009 11:59 pm    Post subject: May 19, 2009 VH Reply with quote

Here is the gird for as far as I could get. After 2 hours I give up. I think I used a x-wing along the way to get here, but that is the only wing---needless to say the puzzle did not fall apart accordingly. Yep, this is before Earl's post, but obviously I look forward to his post to get the solution.

Code:

+-------------+-------------+--------------+
| 4   1  3    | 7  6    8   | 5   2   9    |
| 5   7  2    | 1  3    9   | 8   46  46   |
| 89  6  89   | 2  5    4   | 3   7   1    |
+-------------+-------------+--------------+
| 789 5  4789 | 68 1489 2   | 47  146 3    |
| 2   3  6    | 5  148  17  | 9   14  478  |
| 1   89 4789 | 3  489  67  | 2   5   4678 |
+-------------+-------------+--------------+
| 79  2  5    | 68 18   136 | 147 39  47   |
| 3   4  1    | 9  7    5   | 6   8   2    |
| 6   89 789  | 4  2    13  | 17  39  5    |
+-------------+-------------+--------------+

Play this puzzle online at the Daily Sudoku site
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Tue May 19, 2009 12:50 am    Post subject: Reply with quote

Look for an XY-Wing pivoted in box 6.
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Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS

PostPosted: Tue May 19, 2009 2:08 am    Post subject: May 19 VH Reply with quote

Another Solution:

Coloring in <7> makes R4C7=4 and solves the puzzle. Or the old reliable xy-wing (147) will do it.

Earl
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Luke451



Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

PostPosted: Tue May 19, 2009 3:14 am    Post subject: Reply with quote

There is an empty rectangle that does the same job as Earl's coloring. Check out the locked (7)s in row nine, with the hinge in box 4. Or a W with the two (47) cells and the locked (7)s in c1.

What caught my attention was all those (89)s in the left chute. I haven't found a deal breaker yet, but there is a classic unique rectangle that does a little damage:
Code:
+-------------+-------------+--------------+
| 4   1  3    | 7  6    8   | 5   2   9    |
| 5   7  2    | 1  3    9   | 8   46  46   |
|*89  6 *89   | 2  5    4   | 3   7   1    |
+-------------+-------------+--------------+
|*789 5 *4789 | 68 1489 2   |#47  146 3    |
| 2   3  6    | 5  148  17  | 9   14  478  |
| 1   89 4789 | 3  489  67  | 2   5   4678 |
+-------------+-------------+--------------+
| 79  2  5    | 68 18   136 | 147 39  47   |
| 3   4  1    | 9  7    5   | 6   8   2    |
| 6   89 789  | 4  2    13  | 17  39  5    |
+-------------+-------------+--------------+

The extra candidates in r4c13 are (47). Also in r4 is (47) in r4c7. This means that any (4) or (7) not in the marked cells in r4 can be eliminated. I forget what type UR this is, but whenever I see this setup I turn the pencil over and start erasing.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Tue May 19, 2009 5:01 am    Post subject: Reply with quote

Quote:
I forget what type UR this is

Luke,
its a type 3 or otherwise known as the "unique subset"
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crunched



Joined: 05 Feb 2008
Posts: 168

PostPosted: Tue May 19, 2009 5:14 am    Post subject: Reply with quote

Marty R. wrote:
Look for an XY-Wing pivoted in box 6.


Yep, that is the solution.
I saw that xy-wing pivoted in box 6. I also saw the other xy-wing pivoted in box 6---which does no good. I mistakenly believed that neither xy-wing was worthy!
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ttsmurphy81



Joined: 26 May 2007
Posts: 11

PostPosted: Tue May 19, 2009 1:03 pm    Post subject: Reply with quote

I found the same xy in box six. But had never thought to look for the intersection in that direction. Took me about 35 minutes instead of 15 to solve this puzzle. It was nice, cuz I was hoping for a little more challenging puzzle than as of late.
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Tue May 19, 2009 6:31 pm    Post subject: Reply with quote

There are two ER solutions on <7> using the strong links in either C1 or R9. Either one eliminates the <7> in R4C7. After that it's a breeze.
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