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July 22 VH

 
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nataraj



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

PostPosted: Tue Jul 22, 2008 6:39 am    Post subject: July 22 VH Reply with quote

This time, the "very hard" point comes rather early, while there are still quite a few unsolved cells around, so some searching is required.

xy-wing 29-24-49 row 2 col 8, it takes out 9 in r5c5.

Also, for those who like to exhaust all basic techniques before going "vh", there is a naked quint(?) / hidden pair in box 4 (not needed for the solution).

I also found an xyz-wing but it did not do very much (249 col 4/box 2)
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LloydB



Joined: 09 Jul 2007
Posts: 21
Location: Skagit Co., WA USA

PostPosted: Tue Jul 22, 2008 9:42 am    Post subject: Reply with quote

I also found the xyz wing but it may not have been needed as I later found a 249 xy wing which didn't seem to depend on it. That cracked the puzzle.
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Tue Jul 22, 2008 12:25 pm    Post subject: Reply with quote

I initially found the <249> xy-wing. Then as I was cleaning up, I saw a Type 1 UR on <46> which I took but was apparently not needed to complete the puzzle.

Ted
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Tue Jul 22, 2008 12:32 pm    Post subject: Re: July 22 VH Reply with quote

nataraj wrote:


Also, for those who like to exhaust all basic techniques before going "vh", there is a naked quint(?) / hidden pair in box 4 (not needed for the solution).


Nataraj, it can also be viewed as a naked quad / hidden pair in column 1, which is how I found it.

Ted
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cgordon



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

PostPosted: Tue Jul 22, 2008 7:18 pm    Post subject: Reply with quote

I prefer ER’s and UR’s, but could only find the 249 xy wing. Seems this is all that is available at the VH stage.
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Clement



Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania

PostPosted: Tue Jul 22, 2008 8:21 pm    Post subject: Daily Sudoku: Tue 22 Jul-2008 VH Reply with quote

XY-Wing 249 Pivot {2,4}r2c8 with pincers 29 r2c5 and 49 r5c8 eliminating 9 in r5c5 solving the puzzle.
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cgordon



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

PostPosted: Wed Jul 23, 2008 10:34 pm    Post subject: Reply with quote

Quote:
there is a naked quint hidden pair in box 4


That ain't no quint. A quint is a five job - eg "one of five children born at the same time from the same pregnancy." A quad maybe?
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nataraj



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

PostPosted: Thu Jul 24, 2008 6:24 am    Post subject: Reply with quote

quad, quint ... hm, it probably depends on one's point of view.
In box 4 there is a hidden pair/naked quint
In col 1 there is a hidden pair / naked quad.
When I first did it I missed the box/line elimination that took out a 7 in r7c1...

And, of course the xy wing is there already ...

Code:

+--------------------------+--------------------------+--------------------------+
| 29      5       49       | 2489    7       48       | 1       6       3        |
| 1       7       3        | 6       29      5        | 249     24      8        |
| 269     8       469      | 249     1       3        | 29      7       5        |
+--------------------------+--------------------------+--------------------------+
| 789     19      5        | 89      4       6        | 3       129     27       |
| 6789    469     2        | 3       89      1        | 5       49      467      |
| 369     13469   169      | 7       5       2        | 8       149     46       |
+--------------------------+--------------------------+--------------------------+
| 369     369     679      | 1       238     478      | 246     5       24       |
| 5       136     167      | 24      23      47       | 246     8       9        |
| 4       2       8        | 5       6       9        | 7       3       1        |
+--------------------------+--------------------------+--------------------------+
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