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March 5, vh

 
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crunched



Joined: 05 Feb 2008
Posts: 168
PostPosted: Thu Mar 05, 2009 2:58 am    Post subject: March 5, vh Reply with quote
Here is the grid after basics.

Code:

+---------------+-------------+-----------+
| 9    247  1   | 3   6   27  | 5 28  48  |
| 8    5    6   | 4   1   29  | 7 239 39  |
| 27   247  3   | 5   8   279 | 6 1   49  |
+---------------+-------------+-----------+
| 2357 2379 257 | 279 259 4   | 8 6   1   |
| 6    1    57  | 79  3   8   | 4 579 2   |
| 4    279  8   | 6   259 1   | 3 579 59  |
+---------------+-------------+-----------+
| 125  8    25  | 12  7   3   | 9 4   6   |
| 137  37   9   | 18  4   6   | 2 358 358 |
| 23   6    4   | 289 29  5   | 1 38  7   |
+---------------+-------------+-----------+

Play this puzzle online at the Daily Sudoku site
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Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
PostPosted: Thu Mar 05, 2009 3:09 am    Post subject: Marach 5 VH Reply with quote
The old reliable, an xy-wing (237), will solve it in one step.

Earl
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Clement



Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania
PostPosted: Thu Mar 05, 2009 1:48 pm    Post subject: Daily Sudoku: Thu 5-Mar-2009 VH Reply with quote
XY-Wing {237} Pivot {23}r9c1 eliminating 7's in r1c2 &r3c2 solves the puzzle.
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stevieboy



Joined: 25 Jan 2008
Posts: 31
Location: Michigan
PostPosted: Thu Mar 05, 2009 7:34 pm    Post subject: Reply with quote
It seemed like it took years to find the (237) xy-wing, but, that's what broke it open!
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Fungii



Joined: 06 Mar 2009
Posts: 2
PostPosted: Fri Mar 06, 2009 2:08 am    Post subject: Reply with quote
I'm kind of new to these funky techniques you guys use to solve these puzzles, so I didn't see the (237) xy-wing. Sad

Instead, I worked on the (5,7) r5c3. Both options worked to eliminate the 5 in r4c1, which left the only 5 in that column at r7c1. Once I got that 5 solved, everything else fell into place.

But yeah, I like the (237) xy-wing much better, very elegant. I will get the hang of it one day! Smile
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Fri Mar 06, 2009 4:57 am    Post subject: Reply with quote
Hi Fungii,

Welcome to the forum. Enjoy your stay, lots of funky elegance here!! Wink
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crunched



Joined: 05 Feb 2008
Posts: 168
PostPosted: Fri Mar 06, 2009 6:57 am    Post subject: Reply with quote
So how did your technique solve the puzzle?
I did notice that the 7s in column 3 force an elimination of the rest of the 7s in box 4. Also, more eliminations were made in box 6.
See resulting grid below.
But I could not go any further.
How did you take another step to get rid of the 5 in r4c1?



Fungii wrote:
I'm kind of new to these funky techniques you guys use to solve these puzzles, so I didn't see the (237) xy-wing. Sad

Instead, I worked on the (5,7) r5c3. Both options worked to eliminate the 5 in r4c1, which left the only 5 in that column at r7c1. Once I got that 5 solved, everything else fell into place.

But yeah, I like the (237) xy-wing much better, very elegant. I will get the hang of it one day! Smile


Code:

+-------------+-------------+-----------+
| 9   247 1   | 3   6   27  | 5 28  48  |
| 8   5   6   | 4   1   29  | 7 239 39  |
| 27  247 3   | 5   8   279 | 6 1   49  |
+-------------+-------------+-----------+
| 235 239 257 | 279 259 4   | 8 6   1   |
| 6   1   57  | 79  3   8   | 4 59  2   |
| 4   29  8   | 6   259 1   | 3 7   59  |
+-------------+-------------+-----------+
| 125 8   25  | 12  7   3   | 9 4   6   |
| 137 37  9   | 18  4   6   | 2 358 358 |
| 23  6   4   | 289 29  5   | 1 38  7   |
+-------------+-------------+-----------+

Play this puzzle online at the Daily Sudoku site
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Charlie W



Joined: 26 Feb 2009
Posts: 1
PostPosted: Fri Mar 06, 2009 1:21 pm    Post subject: Reply with quote
Crunched, if r5c3 is 5, then r4c1 is not 5. If r5c3 is 7, then r4c3 and r4c5 are both 25 (via r5c4). These are matched pairs that also eliminate 5 in r4c1.

I'm just getting the hang of these VHs (helped a lot by all the archive puzzles and posts - thanks everyone), and I also used the xy wing for this one.
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crunched



Joined: 05 Feb 2008
Posts: 168
PostPosted: Fri Mar 06, 2009 2:07 pm    Post subject: Reply with quote
Ahhh. Very good. I see the logic in what you did here to eliminate the 5 in r4c1.
Thanks.

Charlie W wrote:
Crunched, if r5c3 is 5, then r4c1 is not 5. If r5c3 is 7, then r4c3 and r4c5 are both 25 (via r5c4). These are matched pairs that also eliminate 5 in r4c1.

I'm just getting the hang of these VHs (helped a lot by all the archive puzzles and posts - thanks everyone), and I also used the xy wing for this one.
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