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30 Oct Hard - is this a VH?

 
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cgordon



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

PostPosted: Tue Oct 30, 2007 12:36 pm    Post subject: 30 Oct Hard - is this a VH? Reply with quote

I tried the Hard puzzle this morning. Should this be a VH? I could only get this far without looking for VH techniques. I'm no doubt missing the obvious.

Code:

+---------------+---------+--------------+
| 8   3    1579 | 2 19 4  | 579 6   1579 |
| 59  4    159  | 6 8  7  | 2   3   159  |
| 2   179  6    | 3 19 5  | 8   179 4    |
+---------------+---------+--------------+
| 4   579  3    | 8 57 1  | 579 2   6    |
| 567 567  2    | 9 57 3  | 1   4   8    |
| 1   8    579  | 4 2  6  | 3   79  579  |
+---------------+---------+--------------+
| 579 2    579  | 1 4  8  | 6   79  3    |
| 3   19   8    | 7 6  29 | 4   5   129  |
| 679 1679 4    | 5 3  29 | 79  8   1279 |
+---------------+---------+--------------+
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Tue Oct 30, 2007 2:51 pm    Post subject: Reply with quote

look at c8
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TexCat



Joined: 07 Jul 2006
Posts: 32

PostPosted: Tue Oct 30, 2007 3:25 pm    Post subject: Reply with quote

I had some trouble with it too. You also need to look at c2 which is where I failed to look originally.
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cgordon



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

PostPosted: Tue Oct 30, 2007 6:56 pm    Post subject: Reply with quote

Yeah - I had actually gotten further than my posted grid but had not copied the grid properly. This was a daft post. My apologies.
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duffy



Joined: 13 Sep 2007
Posts: 26
Location: Toronto Canada

PostPosted: Tue Oct 30, 2007 9:35 pm    Post subject: OB-VIOUS Reply with quote

cgordon,
The Latin root of the word "obvious" is interesting in that it evokes the possibility of its opposite meaning! Indeed an archaic meaning is to stand in the way of something. So I can sympathize with your post, since we all have blind spots from time to time.
It seems to me that a category Hard is frequently so-classed because of a likely need of hidden pairs, and the category itself then often gives me the idea that if I am having trouble I need to look harder for such pairs and/or naked sets.
I was wondering--when my solution was yielding various bivalue cells as it was progressing, and when I initially saw this post--whether it would lead to more discussion of BUG+k situations. I still do not have a full grasp of the arguments explaining BUG theory. Does anyone care to weigh in on this? Question
Meanwhile, I am in your debt, cgordon, as an ethusiastic proponent of ERs! Your contributions and those of others (particularly Marty and Keith) just a few days ago made me stop and absorb the approach to incorporate it into my repertoire, even though I am still very partial to xy- and xyz-wings.
Mr. Green
Don D.
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Thu Nov 01, 2007 11:27 pm    Post subject: Reply with quote

Solving the singles and a pair <79> in B9 gets you to here:
Code:
+-------------+-------------+-------------+
| 8   3   59  | 2   1   4   | 579 6   579 |
| 59  4   1   | 6   8   7   | 2   3   59  |
| 2   7   6   | 3   9   5   | 8   1   4   |
+-------------+-------------+-------------+
| 4   59  3   | 8   57  1   | 579 2   6   |
| 567 56  2   | 9   57  3   | 1   4   8   |
| 1   8   579 | 4   2   6   | 3   79  579 |
+-------------+-------------+-------------+
| 579 2   579 | 1   4   8   | 6   79  3   |
| 3   19  8   | 7   6   29  | 4   5   12  |
| 679 169 4   | 5   3   29  | 79  8   12  |
+-------------+-------------+-------------+

Did you notice the Deadly Pattern 19 - 29 - 12 in R89C269 which says R9C2 must be <6>, and solves the puzzle?

Keith
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