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Jul 23 VH

 
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Clement



Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania
PostPosted: Wed Jul 22, 2015 10:18 pm    Post subject: Jul 23 VH Reply with quote
Code:

+-------+-----------+---------+
| 8 6 3 | 1  57 4   | 57 9  2 |
| 5 4 9 | 6  27 23  | 8  37 1 |
| 1 7 2 | 9  58 38  | 4  35 6 |
+-------+-----------+---------+
| 9 8 6 | 5  3  27  | 1  27 4 |
| 7 2 1 | 4  9  6   | 3  8  5 |
| 3 5 4 | 28 1  278 | 27 6  9 |
+-------+-----------+---------+
| 2 3 5 | 7  6  1   | 9  4  8 |
| 6 1 8 | 3  4  9   | 25 25 7 |
| 4 9 7 | 28 28 5   | 6  1  3 |
+-------+-----------+---------+
XY-Wing pivoted in r2c8; r4c6<>2; stte
Also BUG+1; r6c6=2
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bat999



Joined: 09 Jul 2015
Posts: 55
Location: UK
PostPosted: Thu Jul 23, 2015 12:29 am    Post subject: Reply with quote
Code:
.---------.---------------.-------------.
| 8  6  3 | 1   57   4    | c57   9   2 |
| 5  4  9 | 6   27   23   |  8    37  1 |
| 1  7  2 | 9   58  e38   |  4   d35  6 |
:---------+---------------+-------------:
| 9  8  6 | 5   3    27   |  1    27  4 |
| 7  2  1 | 4   9    6    |  3    8   5 |
| 3  5  4 | 28  1   a27-8 | b27   6   9 |
:---------+---------------+-------------:
| 2  3  5 | 7   6    1    |  9    4   8 |
| 6  1  8 | 3   4    9    |  25   25  7 |
| 4  9  7 | 28  28   5    |  6    1   3 |
'---------'---------------'-------------'
AIC: (7)r6c6 = r6c7 - (7=5)r1c7 - (5=3)r3c8 - (3=8)r3c6 => -8 r6c6; stte
Cool
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hughwill



Joined: 05 Apr 2010
Posts: 424
Location: Birmingham UK
PostPosted: Thu Jul 23, 2015 9:23 am    Post subject: Reply with quote
bat999 wrote:
Code:
.---------.---------------.-------------.
| 8  6  3 | 1   57   4    | c57   9   2 |
| 5  4  9 | 6   27   23   |  8    37  1 |
| 1  7  2 | 9   58  e38   |  4   d35  6 |
:---------+---------------+-------------:
| 9  8  6 | 5   3    27   |  1    27  4 |
| 7  2  1 | 4   9    6    |  3    8   5 |
| 3  5  4 | 28  1   a27-8 | b27   6   9 |
:---------+---------------+-------------:
| 2  3  5 | 7   6    1    |  9    4   8 |
| 6  1  8 | 3   4    9    |  25   25  7 |
| 4  9  7 | 28  28   5    |  6    1   3 |
'---------'---------------'-------------'
AIC: (7)r6c6 = r6c7 - (7=5)r1c7 - (5=3)r3c8 - (3=8)r3c6 => -8 r6c6; stte
Cool


For those in the know- don't you get the same result with a BUG+1
setting r6c6 to 2? (I have only a vague knowledge of such things...)

Hugh
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dongrave



Joined: 06 Mar 2014
Posts: 568
PostPosted: Thu Jul 23, 2015 5:10 pm    Post subject: Reply with quote
I see two 'standard' VH solutions. Clement's 37-2 XY-wing with pivot at r2c8 so r4c6<>2 and the 23-7 XY-wing with pivot at r2c6 so r4c8<>7.
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Thu Jul 23, 2015 5:52 pm    Post subject: Reply with quote
Code:

+-------+-----------+---------+
| 8 6 3 | 1  57 4   | 57 9  2 |
| 5 4 9 | 6  27 23  | 8  37 1 |
| 1 7 2 | 9  58 38  | 4  35 6 |
+-------+-----------+---------+
| 9 8 6 | 5  3  27  | 1  27 4 |
| 7 2 1 | 4  9  6   | 3  8  5 |
| 3 5 4 | 28 1  278 | 27 6  9 |
+-------+-----------+---------+
| 2 3 5 | 7  6  1   | 9  4  8 |
| 6 1 8 | 3  4  9   | 25 25 7 |
| 4 9 7 | 28 28 5   | 6  1  3 |
+-------+-----------+---------+

Play this puzzle online at the Daily Sudoku site

W=Wing (27) in b25 with SL 7 in c8 => -2r2c6.

Hugh, yes the BUG yields the same solution.
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Thu Jul 23, 2015 6:44 pm    Post subject: Reply with quote
bat999 wrote:
Code:
.---------.---------------.-------------.
| 8  6  3 | 1   57   4    | c57   9   2 |
| 5  4  9 | 6   27   23   |  8    37  1 |
| 1  7  2 | 9   58  e38   |  4   d35  6 |
:---------+---------------+-------------:
| 9  8  6 | 5   3    27   |  1    27  4 |
| 7  2  1 | 4   9    6    |  3    8   5 |
| 3  5  4 | 28  1   a27-8 | b27   6   9 |
:---------+---------------+-------------:
| 2  3  5 | 7   6    1    |  9    4   8 |
| 6  1  8 | 3   4    9    |  25   25  7 |
| 4  9  7 | 28  28   5    |  6    1   3 |
'---------'---------------'-------------'
AIC: (7)r6c6 = r6c7 - (7=5)r1c7 - (5=3)r3c8 - (3=8)r3c6 => -8 r6c6; stte
Cool


Bat, I don't know what's going on with that chain. Normally when you start out with -7, the chain ends with =7, creating pincers on 7. In this case, the chain says if r6c6<>7, then r3c6=8. I can't see an elimination there. Now let's look at the opening term's opposite, i.e. r6c=7.which, does indeed result in r6c6-8.
The reader can't see that conclusion from the chain so he has to assume the opening term's opposite and carry things out to see a conclusion.

I'd look for a more straightforward XY-Chain, Such as, (3=2)r2c6-(2=7)r4c6-(7=2)r4c8 -(2=5)r8c8-(5=3)r3c8=>-3r2c8,r3c6
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bat999



Joined: 09 Jul 2015
Posts: 55
Location: UK
PostPosted: Thu Jul 23, 2015 7:34 pm    Post subject: Reply with quote
Marty R. wrote:
... In this case, the chain says if r6c6<>7, then r3c6=8. I can't see an elimination there...

Code:
.---------.---------------.-------------.
| 8  6  3 | 1   57   4    | c57   9   2 |
| 5  4  9 | 6   27   23   |  8    37  1 |
| 1  7  2 | 9   58  e38   |  4   d35  6 |
:---------+---------------+-------------:
| 9  8  6 | 5   3    27   |  1    27  4 |
| 7  2  1 | 4   9    6    |  3    8   5 |
| 3  5  4 | 28  1   a27-8 | b27   6   9 |
:---------+---------------+-------------:
| 2  3  5 | 7   6    1    |  9    4   8 |
| 6  1  8 | 3   4    9    |  25   25  7 |
| 4  9  7 | 28  28   5    |  6    1   3 |
'---------'---------------'-------------'
AIC: (7)r6c6 = r6c7 - (7=5)r1c7 - (5=3)r3c8 - (3=8)r3c6 => -8 r6c6; stte
Cool

Hi
It's saying...
If r6c6=7 then r6c6<>8 (obviously).
If r6c6<>7 then r3c6=8 (which would kill an 8 in r6c6).

Either way, r6c6 can't be an 8.
=> -8 r6c6
Cool
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Thu Jul 23, 2015 9:08 pm    Post subject: Reply with quote
Bat, I see what you're doing and agree with the conclusion. I saw the way the chain started and was expecting to see a 7 in the final term to create the pincers, so that is why I replied. I guess I was a little confused and it just took me a little while. Sorry, I overreacted.
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bat999



Joined: 09 Jul 2015
Posts: 55
Location: UK
PostPosted: Thu Jul 23, 2015 10:11 pm    Post subject: Reply with quote
Marty R. wrote:
... overreacted...
No problem. Smile
It's good for you to ask the question, made me check again that I hadn't goofed. Wink
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