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March 15 VH

 
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Earl



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

PostPosted: Mon Mar 15, 2010 3:35 am    Post subject: March 15 VH Reply with quote

Could not find a single step. Norm?

A Solution: x-wing (1), then xy-wing (179) with pivot at R6C4 eliminates 7 in R5C1


Early Earl


Last edited by Earl on Mon Mar 15, 2010 10:44 pm; edited 1 time in total
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Marty R.



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

PostPosted: Mon Mar 15, 2010 4:58 am    Post subject: Reply with quote

I used your first step, but didn't see your second, so I finished with a four-cell XY-Chain.
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cgordon



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

PostPosted: Mon Mar 15, 2010 6:31 pm    Post subject: Reply with quote

I also did not see Earl's wing

First I knocked off the <7>s in R3/Box 3 with a Type 4 UR 27.

And then used the <7> s in C6 for a kind of double ER. If it’s the bottom <7> in C6, the ER in B4 knocks off the <7> in R1C2. And if it’s top <7> there’s a reverse flip ER using B3 that also eliminates the same <7>.

But as brilliant as that was, it still did not get me very far - and I ain't into chains. Could this be a V VH?

Code:
            
+-------+-------+-------+   
| . 7 . | . . . | . 7 7 |   
| 7 . . | . . 7 | . . 7 |   
| 7 7 . | . 7 . | . . . |   
+-------+-------+-------+   
| . 7 . | . . . | . 7 . |   
| 7 . . | . . 7 | 7 . . |   
| . 7 . | . 7 . | 7 . . |   
+-------+-------+-------+   
| . . . | . . . | . . . |   
| . . . | . . . | 7 . 7 |   
| . . . | . . . | . . . |
+-------+-------+-------+


[/code][/quote]
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Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Mon Mar 15, 2010 10:28 pm    Post subject: Reply with quote

Marty, I did it the same way you did, plus one more step: X-wing on 2, then chain 17, then XY-wing 167.
I'm normally not a big fan of chains either, but for some reason I found this one really easy to follow.
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Marty R.



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

PostPosted: Mon Mar 15, 2010 11:55 pm    Post subject: Reply with quote

I tried it again, this time online instead of pencil and paper, and this time I saw the 197 XY-Wing.

This is what I saw after basics and the X-Wing on 1:

Code:

+------------+------------+-------------+
| 4   157 3  | 2   8   6  | 9   17 57   |
| 167 2   8  | 15  9   17 | 3   4  567  |
| 167 579 69 | 145 457 3  | 127 8  2567 |
+------------+------------+-------------+
| 2   17  46 | 3   46  8  | 5   17 9    |
| 167 3   49 | 459 45  17 | 167 2  8    |
| 8   79  5  | 19  67  2  | 167 3  4    |
+------------+------------+-------------+
| 5   4   2  | 7   1   9  | 8   6  3    |
| 9   6   1  | 8   3   4  | 27  5  27   |
| 3   8   7  | 6   2   5  | 4   9  1    |
+------------+------------+-------------+

Play this puzzle online at the Daily Sudoku site
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Thu Mar 18, 2010 3:56 am    Post subject: Reply with quote

Quote:
Could not find a single step. Norm?


Code:
+----------------+----------------+---------------+
| 4    157   3   | 2     8     6  | 9    17  57   |
| 167  2     8   | 15    9     17 | 3    4   567  |
| 167  1579  69  | 145   457   3  | 127  8   2567 |
+----------------+----------------+---------------+
| 2    17    46  | 3     467   8  | 5    17  9    |
| 167  3     469 | 1459  4567  17 | 167  2   8    |
| 8    179   5   | 19    67    2  | 167  3   4    |
+----------------+----------------+---------------+
| 5    4     2   | 7     1     9  | 8    6   3    |
| 9    6     1   | 8     3     4  | 27   5   27   |
| 3    8     7   | 6     2     5  | 4    9   1    |
+----------------+----------------+---------------+


the x-wing can be used as part of the fin for the xy-wing.
either the xy-wing {179} is true => r6c5 <> 7

or

(1)r6c1 - (1)r4c2 = (1)r4c8 - (1)r1c8 = (1)r1c2 - (1)r23c1 = (1)r5c1 - (1=7)r5c6

either way the 7 in r5c6 is true and the 7 in r6c5 is toast.

x-wing in red
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Fri Mar 19, 2010 1:48 pm    Post subject: Reply with quote

storm_norm wrote:
Quote:
Could not find a single step. Norm?


Code:
+----------------+----------------+---------------+
| 4    157   3   | 2     8     6  | 9    17  57   |
| 167  2     8   | 15    9     17 | 3    4   567  |
| 167  1579  69  | 145   457   3  | 127  8   2567 |
+----------------+----------------+---------------+
| 2    17    46  | 3     467   8  | 5    17  9    |
| 167  3     469 | 1459  4567  17 | 167  2   8    |
| 8    179   5   | 19    67    2  | 167  3   4    |
+----------------+----------------+---------------+
| 5    4     2   | 7     1     9  | 8    6   3    |
| 9    6     1   | 8     3     4  | 27   5   27   |
| 3    8     7   | 6     2     5  | 4    9   1    |
+----------------+----------------+---------------+


the x-wing can be used as part of the fin for the xy-wing.
either the xy-wing {179} is true => r6c5 <> 7

or

(1)r6c1 - (1)r4c2 = (1)r4c8 - (1)r1c8 = (1)r1c2 - (1)r23c1 = (1)r5c1 - (1=7)r5c6

either way the 7 in r5c6 is true and the 7 in r6c5 is toast.

x-wing in red


Norm, I just got around to looking at your post and am having a problem following your logic.

I see a finned xy-wing condition with vertex 79 in r6c2, pincer 17 in r4c2, pincer 19 in r6c4 and fin 1 in r6c2. However I do not see how the xy-wing forces r5c6=7.

Also, the AIC for the fin may have a typo since is starts in cell r6c1 rather than r6c2.

Ted
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