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June 21 VH

 
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kragzy



Joined: 01 May 2007
Posts: 112
Location: Australia

PostPosted: Mon Jun 21, 2010 12:21 am    Post subject: June 21 VH Reply with quote

The shortest day on this side of the globe, and the longest puzzle, for me at least. Look carefully for hidden pairs in this messy puzzle. I missed one and wasted at least 30 minutes searching for 'advanced' tricks when 'simple' basics would have cleared so much dross. An XY wing does it eventually.
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sdq_pete



Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL

PostPosted: Mon Jun 21, 2010 11:50 am    Post subject: Reply with quote

Yes, I applied the XY-wing quite some way before finishing the basics.
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gindaani



Joined: 06 Mar 2009
Posts: 79

PostPosted: Mon Jun 21, 2010 3:53 pm    Post subject: Reply with quote

248 xy wing did it for me.
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George Woods



Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK

PostPosted: Mon Jun 21, 2010 3:54 pm    Post subject: Hard very hard! Reply with quote

I agree. Although the XY wing appeared after only 9 entries It was still Hard to finish. So much so I thought I must have missed something so went to DRAW/PLAY and put a 4 into r8c3 (thus simulating the effect of the XY wing) Sure enough GRADE now analysed the puzzle as HARD -after the so called "advanced move" doing this in DRAW/PLAY usually gives an easy or a medium graded residual!
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gindaani



Joined: 06 Mar 2009
Posts: 79

PostPosted: Mon Jun 21, 2010 4:04 pm    Post subject: Reply with quote

After the 248 xy wing, there is a naked quad and the puzzle unravels easily after that.

Here is the puzzle after basics.

Code:

+-------------------+--------------+---------------+
| 1245 13489 124589 | 48  6   1235 | 7    2348 238 |
| 6    7     2458   | 48  25  235  | 2348 1    9   |
| 124  1348  1248   | 7   12  9    | 5    2348 6   |
+-------------------+--------------+---------------+
| 45   48    6      | 1   3   7    | 28   9    258 |
| 3    19    19     | 25  8   25   | 6    7    4   |
| 7    2     58     | 6   9   4    | 1    358  358 |
+-------------------+--------------+---------------+
| 9    146   7      | 3   125 8    | 24   2456 125 |
| 8    5     124    | 29  7   126  | 2349 2346 123 |
| 12   16    3      | 259 4   1256 | 289  2568 7   |
+-------------------+--------------+---------------+

Play this puzzle online at the Daily Sudoku site
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keith



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

PostPosted: Mon Jun 21, 2010 6:20 pm    Post subject: Reply with quote

For once, a puzzle worth the rating.

Keith
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cgordon



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

PostPosted: Mon Jun 21, 2010 7:41 pm    Post subject: Reply with quote

I too found the xy wing but after trying all the VH weapons in my arsenal -I was stumped. I had to refer to this Forum for the solution. Even after reading there was a quad it still took me a long time to find it. This proves my theory (which I haven’t published yet) that VH techniques are just simple tools and that the real work is often in the basics. Thus a good Hard is often more challenging than a Very Hard.
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gindaani



Joined: 06 Mar 2009
Posts: 79

PostPosted: Mon Jun 21, 2010 7:54 pm    Post subject: Reply with quote

I agree completely. On the average, I find hard puzzles more difficult than very hard puzzles. The VH puzzles involve more advanced techniques, but those techniques are generally easy to spot once you learn them. The H puzzles usually involve hidden pairs, hidden triplets, and quads which can be harder to spot.

This should be the new standard for a VH puzzle. It requires and advanced technique to get to a H puzzle.

I went back an did the VH puzzles from 2005 and 2006. I didn't use a single wing or "advanced" technique. They would all be called Hard (at best) now. Interesting how the definition of "Very Hard" evolves. Razz
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cgordon



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

PostPosted: Mon Jun 21, 2010 8:57 pm    Post subject: Reply with quote

Quote:
Interesting how the definition of "Very Hard" evolves.

The wife and I were discussing the same thing.
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keith



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

PostPosted: Mon Jun 21, 2010 9:41 pm    Post subject: Reply with quote

cgordon wrote:
Quote:
Interesting how the definition of "Very Hard" evolves.

The wife and I were discussing the same thing.

And, I hope, you were talking about Sudoku Laughing

Yes, a few years ago the definition of "Very Hard" changed to include puzzles that can be solved with these advanced techniques: X-wing, XY-wing, and / or XYZ-wing.

To be sure, many use other techniques like Unique Rectangles, W-wings and M-wings, but these are not "required".

I find most of the VH puzzles pretty boring - do the easy basics and find one X/XY/XYZ-wing.

I find the "Hard" puzzles much more entertaining, particularly if attempted without pencil marks.

Keith
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gindaani



Joined: 06 Mar 2009
Posts: 79

PostPosted: Mon Jun 21, 2010 9:48 pm    Post subject: Reply with quote

keith wrote:
cgordon wrote:
Quote:
Interesting how the definition of "Very Hard" evolves.

The wife and I were discussing the same thing.

And, I hope, you were talking about Sudoku Laughing

ROFL!! Laughing
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Tue Jun 22, 2010 9:34 am    Post subject: Reply with quote

Keith,

I had no idea you were such a Finbarr Saunders! Laughing
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Tue Jun 22, 2010 2:46 pm    Post subject: Reply with quote

Mogulmeister wrote:

I had no idea you were such a Finbarr Saunders! Laughing


Do they get Viz in Michigan? Chortle Chortle..
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keith



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

PostPosted: Tue Jun 22, 2010 4:12 pm    Post subject: Reply with quote

Note that the joke is cgordon's, not mine ...

Keith
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Tue Jun 22, 2010 7:51 pm    Post subject: Reply with quote

...but he was just talking about sudoku.......... Laughing
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keith



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

PostPosted: Tue Jun 22, 2010 9:11 pm    Post subject: Reply with quote

Mogulmeister wrote:
...but he was just talking about sudoku.......... Laughing

No, he was talking about the definition of "Very Hard". Shocked

(Or was it naked pairs?)

Keith
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Thu Jun 24, 2010 11:32 am    Post subject: Reply with quote

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Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Thu Jun 24, 2010 10:52 pm    Post subject: Reply with quote

Geez, I take a break from Sudoku for a few weeks and look what happens to the Forum!
Very Happy
LOL!
Good puzzle too.
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