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Mar 17 VH

 
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Clement



Joined: 24 Apr 2006
Posts: 639
Location: Dar es Salaam Tanzania

PostPosted: Fri Mar 16, 2012 10:51 pm    Post subject: Mar 17 VH Reply with quote

After the Basics
Code:

+--------+------------+----------+
| 9  8 3 | 7  1   26  | 26 4  5  |
| 6  4 1 | -89 258 259 | 28 3  7  |
| 7  2 5 | 3  68  4   | 1  68 9  |
+--------+------------+----------+
| 1  9 4 | 68 27  27  | 3  5  68 |
| 38 5 2 | 4  9   36  | 68 7  1  |
| 38 7 6 | 1  58  35  | 4  9  2  |
+--------+------------+----------+
| 5  3 7 | 2  4   1   | 9  68 68 |
| 4  1 8 | 69 67  679 | 5  2  3  |
| 2  6 9 | 5  3   8   | 7  1  4  |
+--------+------------+----------+
Remote pairs on 68; r2c4<>8 solves it.
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Marty R.



Joined: 12 Feb 2006
Posts: 5063
Location: Rochester, NY, USA

PostPosted: Sat Mar 17, 2012 3:46 am    Post subject: Re: Mar 17 VH Reply with quote

Clement wrote:
After the Basics
Code:

+--------+------------+----------+
| 9  8 3 | 7  1   26  | 26 4  5  |
| 6  4 1 | -89 258 259 | 28 3  7  |
| 7  2 5 | 3  68  4   | 1  68 9  |
+--------+------------+----------+
| 1  9 4 | 68 27  27  | 3  5  68 |
| 38 5 2 | 4  9   36  | 68 7  1  |
| 38 7 6 | 1  58  35  | 4  9  2  |
+--------+------------+----------+
| 5  3 7 | 2  4   1   | 9  68 68 |
| 4  1 8 | 69 67  679 | 5  2  3  |
| 2  6 9 | 5  3   8   | 7  1  4  |
+--------+------------+----------+
Remote pairs on 68; r2c4<>8 solves it.

I used the 896 XY-Wing pivoted in r2c4; r8c5<>6. I can't find the Remote Pairs. The closest I can come is Simple Coloring, 68-68-68-28.
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Clement



Joined: 24 Apr 2006
Posts: 639
Location: Dar es Salaam Tanzania

PostPosted: Sat Mar 17, 2012 7:10 am    Post subject: Re: Mar 17 VH Reply with quote

Marty R. wrote:
Clement wrote:
After the Basics
Code:

+--------+------------+----------+
| 9  8 3 | 7  1   26  | 26 4  5  |
| 6  4 1 | -89 258 259 | 28 3  7  |
| 7  2 5 | 3  68  4   | 1  68 9  |
+--------+------------+----------+
| 1  9 4 | 68 27  27  | 3  5  68 |
| 38 5 2 | 4  9   36  | 68 7  1  |
| 38 7 6 | 1  58  35  | 4  9  2  |
+--------+------------+----------+
| 5  3 7 | 2  4   1   | 9  68 68 |
| 4  1 8 | 69 67  679 | 5  2  3  |
| 2  6 9 | 5  3   8   | 7  1  4  |
+--------+------------+----------+
Remote pairs on 68; r2c4<>8 solves it.

I used the 896 XY-Wing pivoted in r2c4; r8c5<>6. I can't find the Remote Pairs. The closest I can come is Simple Coloring, 68-68-68-28.
The remote pairs I am refering in my Grid are as follows:
Code:

+--------+------------+----------+
| 9  8 3 | 7  1   26  | 26 4  5  |
| 6  4 1 | 89 258 259 | 28 3  7  |
| 7  2 5 | 3  A68  4   | 1  B68 9  |
+--------+------------+----------+
| 1  9 4 | F68 27  27  | 3  5  E68 |
| 38 5 2 | 4  9   36  | 68 7  1  |
| 38 7 6 | 1  58  35  | 4  9  2  |
+--------+------------+----------+
| 5  3 7 | 2  4   1   | 9  C68 D68 |
| 4  1 8 | 69 67  679 | 5  2  3  |
| 2  6 9 | 5  3   8   | 7  1  4  |
+--------+------------+----------+
A->B->C->D->E->F. A and F can see r2c4; r2c4<>8. Pairs can be used to remove a single candidate. If you like you can refer this route as singles chains on 8.
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skegbyrd



Joined: 17 Mar 2012
Posts: 2

PostPosted: Sat Mar 17, 2012 9:58 am    Post subject: Reply with quote

I don't understand x wings. I solved it with, r2 c 5, 6 & 7. 258, 25, 28 so r2 c4 must be 9.
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hughwill



Joined: 05 Apr 2010
Posts: 142
Location: Birmingham UK

PostPosted: Sat Mar 17, 2012 10:15 am    Post subject: Re: Mar 17 VH Reply with quote

Clement's chain also sets r6c5 to 5 solving the puzzle. I couldn't get as far as
Skegbyrd with basics to remove the 2 from r2c5 and the 9 from r2c6......

But the humdrum XY wing 896 did the job for me- I'm sure someone
(Marty, Arkitech?)will point Skegbyrd in the direction of one of the great
explanations of wings opening up a whole new world of solving!
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arkietech



Joined: 31 Jul 2008
Posts: 1686
Location: Northwest Arkansas USA

PostPosted: Sat Mar 17, 2012 11:47 am    Post subject: Reply with quote

skegbyrd wrote:
I don't understand x wings.


The best way to understand the xy-wing is go to the pivot. In this case it is r2c4 with two possible candidates 8 or 9.

If r2c4 is an 8 then r2c5 is a 6.

If r2c4 is an 9 then r8c4 is a 6.

This means r8c5 cannot be a 6.

This solves ther puzzle .. (only singles remain).

Hope this helps.
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Marty R.



Joined: 12 Feb 2006
Posts: 5063
Location: Rochester, NY, USA

PostPosted: Sat Mar 17, 2012 12:01 pm    Post subject: Reply with quote

Quote:
A->B->C->D->E->F. A and F can see r2c4; r2c4<>8.


Clement, thanks for straightening me out. I should have been able to spot that. Embarassed
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Marty R.



Joined: 12 Feb 2006
Posts: 5063
Location: Rochester, NY, USA

PostPosted: Sat Mar 17, 2012 12:11 pm    Post subject: Reply with quote

Quote:
I don't understand x wings.


Skegbyrd, this explains many of the techniques that are frequently used and discussed here.

http://www.sadmansoftware.com/sudoku/solvingtechniques.htm
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skegbyrd



Joined: 17 Mar 2012
Posts: 2

PostPosted: Sun Mar 18, 2012 9:23 am    Post subject: xy wing Reply with quote

I think I have it but you made it a little more difficult saying r2 c5 is a 6 when I think you meant r3 c5. I have read various articles trying to explain them but yours was the best. Thanks.
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