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7/18 a moderate VH

 
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Earl



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

PostPosted: Wed Jul 18, 2007 6:46 pm    Post subject: 7/18 a moderate VH Reply with quote

I used only standard techniques for this one.
Two xyz-wings which opened the way for three xy-wings.
Any one find a more direct solution?

Earl
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cgordon



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

PostPosted: Wed Jul 18, 2007 9:12 pm    Post subject: Reply with quote

I've been doing VHs for a few months now and have always been able to solve them (eventually) with x to xyz wings. Unless I made a lucky error with this one, it seemed to require just the basic elimination techniques of a medium to hard.

Ironically, I thought the previous VH (July 16) was the hardest I'd come across. After 4 wing steps I was still stuck - until Mogulmeister directed me towards an explanation of xy chains. But to be honest, I found the chain thing a bit too arbitrary - like finding you way out of a maze by trial and error. Unless there's a technique for spotting the route - it didn't seem much different from the trial and error iteration methods I used for the VHs before I learnt about wings.
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Marty R.



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

PostPosted: Wed Jul 18, 2007 10:28 pm    Post subject: Reply with quote

One XYZ and one XY did it for me.
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dldcamp



Joined: 29 May 2007
Posts: 15
Location: Florida

PostPosted: Wed Jul 18, 2007 10:39 pm    Post subject: this is NOT easy for me Reply with quote

I am lost with the XYZ pattern you are describing. Since I am totally lost with this "new" skill, can someone very painstakingly explain it to me step by step?
+-------------+-------------+--------------+
| 5 1 4 | 8 7 2 | 3 9 6 |
| 8 27 9 | 4 6 3 | 5 27 1 |
| 27 3 6 | 15 159 19 | 4 8 27 |
+-------------+-------------+--------------+
| 167 67 15 | 9 3 168 | 2 4 578 |
| 4 9 135 | 2 15 168 | 68 1567 3578 |
| 136 8 2 | 156 4 7 | 9 156 35 |
+-------------+-------------+--------------+
| 1236 4 13 | 7 19 169 | 68 256 258 |
| 9 26 7 | 3 8 5 | 1 26 4 |
| 16 5 8 | 16 2 4 | 7 3 9 |
+-------------+-------------+--------------+
[/code]
[url=http://www.dailysudoku.com/sudoku/play.


Thanks
DLD Camp
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Marty R.



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

PostPosted: Wed Jul 18, 2007 11:17 pm    Post subject: Re: this is NOT easy for me Reply with quote

dldcamp wrote:
I am lost with the XYZ pattern you are describing. Since I am totally lost with this "new" skill, can someone very painstakingly explain it to me step by step?
Code:
+-------------+-------------+--------------+
| 5    1  4   | 8   7   2   | 3  9    6    |
| 8    27 9   | 4   6   3   | 5  27   1    |
| 27   3  6   | 15  159 19  | 4  8    27   |
+-------------+-------------+--------------+
| 167  67 15  | 9   3   168 | 2  4    578  |
| 4    9  135 | 2   15  168 | 68 1567 3578 |
| 136  8  2   | 156 4   7   | 9  156  35   |
+-------------+-------------+--------------+
| 1236 4  13  | 7   19  169 | 68 256  258  |
| 9    26 7   | 3   8   5   | 1  26   4    |
| 16   5  8   | 16  2   4   | 7  3    9    |
+-------------+-------------+--------------+

[url=http://www.dailysudoku.com/sudoku/play.

Thanks
DLD Camp



The XYZ-Wing is in r4c1, r4c2 and r9c1. That technique is explained here (and probably many other places too):

http://www.brainbashers.com/sudokuxyzwing.asp
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cgordon



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

PostPosted: Thu Jul 19, 2007 12:43 am    Post subject: Reply with quote

I think I may have erred in my presumption that this was not a 'Very Hard' puzzle. Wouldn't be the first time - but I promise the last. Anyway, 3rd time around I found an xy wing with pivot R4C2. At least I hope I did.
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dldcamp



Joined: 29 May 2007
Posts: 15
Location: Florida

PostPosted: Thu Jul 19, 2007 1:26 pm    Post subject: Yippee! Reply with quote

Thanks Marty R. and CGordon!!! It seems I finally Understand these two techniques. Now if I can only spot them on my own. The Brainbashers site was perfect at explaining everything. It seems that the most helpful clue was the "Buddies" entry. I printed out all three entries and will keep them by my side.
Thanks again for your patience and helpful "hints." Very Happy
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Fri Jul 20, 2007 10:33 am    Post subject: Reply with quote

Quote:
But to be honest, I found the chain thing a bit too arbitrary - like finding you way out of a maze by trial and error


That comes with practice - as I've said before when you start to get a lot of bivalues and our usual XY and XWZ wings are not forthcoming it is a powerful techniques - the skill is in spotting the eliminating pincers. XY wings are incredibly powerful - especially as we approach the end game of a puzzle.
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PouLeeps



Joined: 19 Jun 2007
Posts: 6
Location: Lismore, Australia

PostPosted: Fri Jul 20, 2007 2:45 pm    Post subject: Reply with quote

Could someone tell me where to go from here please?

[/code]
+-------------+-------------+--------------+
| 5 1 4 | 8 7 2 | 3 9 6 |
| 8 27 9 | 4 6 3 | 5 27 1 |
| 27 3 6 | 15 159 19 | 4 8 27 |
+-------------+-------------+--------------+
| 67 67 15 | 9 3 18 | 2 4 58 |
| 4 9 135 | 2 15 168 | 68 1567 3578 |
| 13 8 2 | 156 4 7 | 9 156 35 |
+-------------+-------------+--------------+
| 1236 4 13 | 7 19 169 | 68 56 258 |
| 9 26 7 | 3 8 5 | 1 26 4 |
| 16 5 8 | 16 2 4 | 7 3 9 |
+-------------+-------------+--------------+
Code:
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jLo



Joined: 30 Apr 2007
Posts: 55

PostPosted: Fri Jul 20, 2007 3:39 pm    Post subject: Reply with quote

PouLeeps wrote:
Could someone tell me where to go from here please?



Look in Box 4 for the pivot of an XY-wing. Once you spot that you will be done.
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cgordon



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

PostPosted: Fri Jul 20, 2007 4:32 pm    Post subject: Reply with quote

Quote:
Thanks Marty R. and CGordon!!!


I don't know what for mate!! The logic in my second post was as screwed up as the first. But I believe JLo is alluding to the 13 pivot in C1 which gets rid of the 5 in R4C9. Not an easy one to spot.
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PouLeeps



Joined: 19 Jun 2007
Posts: 6
Location: Lismore, Australia

PostPosted: Sat Jul 21, 2007 4:38 am    Post subject: Reply with quote

Thanks jLo
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