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Aug 31 VH

 
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Clement



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

PostPosted: Mon Aug 30, 2010 10:56 pm    Post subject: Aug 31 VH Reply with quote

Two steps(XY-Wings):-
1) XY-Wing 14 16 46 Pivoted in r9c1 removes 4 in r4c4 opens another
2) XY-Wing 67 47 46 with Pivot in r1c1 eliminating 6 in r7c6 solving the puzzle.
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Marty R.



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

PostPosted: Tue Aug 31, 2010 4:18 am    Post subject: Reply with quote

I would probably not have used this DP had Nataraj not posted his very similar DP here just today:

http://www.dailysudoku.co.uk/sudoku/forums/viewtopic.php?t=5035

Here's my grid after basics:

Code:

+-------------+-------------+---------+
| 478  1  3   | 4678 48  46 | 2  9 5  |
| 89   6  2   | 5    19  3  | 18 4 7  |
| 4789 5  47  | 478  19  2  | 6  3 18 |
+-------------+-------------+---------+
| 14   9  145 | 48   458 7  | 3  2 6  |
| 2    8  46  | 3    46  1  | 7  5 9  |
| 3    7  56  | 2    56  9  | 48 1 48 |
+-------------+-------------+---------+
| 67   34 9   | 1    27  46 | 5  8 23 |
| 5    34 17  | 9    27  8  | 14 6 23 |
| 16   2  8   | 46   3   5  | 9  7 14 |
+-------------+-------------+---------+

Play this puzzle online at the Daily Sudoku site

There is a potential DP 45-46-56 in r456, c35. The DP can be broken up by the 8 in r4c5 or the 1 in r4c3. The 8 proves a 1 in r9c1 and this acts as a pincer with the 1 in r4c3, eliminating 1s in boxes 47, solving the puzzle.
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kuskey



Joined: 10 Dec 2008
Posts: 141
Location: Pembroke, NH

PostPosted: Tue Aug 31, 2010 4:34 am    Post subject: 31 Aug VH Reply with quote

I agree with Clement but would add that the 467 xy-wing can be played two ways;with the pivot at r1c1 eliminating 6 in r7c6, or with the pivot at r7c1 eliminating 4 at r1c6 - somewhat unusual, I think.
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Clement



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

PostPosted: Tue Aug 31, 2010 7:02 pm    Post subject: Aug 31 VH Reply with quote

Kuskey,
It is quite O.K. It occurs several times for the same configuration in an XY wing to have different pivots. I did not notice that one.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Tue Aug 31, 2010 8:00 pm    Post subject: Reply with quote

this is Marty's brilliant find.


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Marty R.



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

PostPosted: Tue Aug 31, 2010 9:27 pm    Post subject: Reply with quote

Quote:
this is Marty's brilliant find.

Thanks very much, but most of the credit should probably go to Nataraj.
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Luke451



Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

PostPosted: Wed Sep 01, 2010 1:53 pm    Post subject: Reply with quote

It has been interesting to watch the emergence of BUG-Lite use lately. With Marty's find, along with Nataraj's and Keith's last month, we'll have to retire the "rare" label soon Very Happy .

Since this BUG-Lite provides the strong link (1)r4c3=(8)r4c5, I would express it as an AIC.
Code:
 *-----------------------------------------------------------*
 | 478   1     3     | 4678  48    46    | 2     9     5     |
 | 89    6     2     | 5     19    3     | 18    4     7     |
 | 4789  5     47    | 478   19    2     | 6     3     18    |
 |-------------------+-------------------+-------------------|
 | 14    9     145   | 48    458   7     | 3     2     6     |
 | 2     8     46    | 3     46    1     | 7     5     9     |
 | 3     7     56    | 2     56    9     | 48    1     48    |
 |-------------------+-------------------+-------------------|
 | 67    34    9     | 1     27    46    | 5     8     23    |
 | 5     34    17    | 9     27    8     | 14    6     23    |
 | 16    2     8     | 46    3     5     | 9     7     14    |
 *-----------------------------------------------------------*

(1)r4c3=(8)r4c5-(8=4)r4c4-(4=6)r9c4-(6=1)r9c1 =>r4c1<>1
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sheryl



Joined: 24 Sep 2007
Posts: 64
Location: New York

PostPosted: Wed Sep 01, 2010 2:39 pm    Post subject: where are the xy wings Reply with quote

clement,
can you please specify row and columns for the first 14, 16, 46 xy wing. i have all those numbers but they don't form an xy wing for me.
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Marty R.



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

PostPosted: Wed Sep 01, 2010 3:57 pm    Post subject: Re: where are the xy wings Reply with quote

sheryl wrote:
clement,
can you please specify row and columns for the first 14, 16, 46 xy wing. i have all those numbers but they don't form an xy wing for me.

I'm not Clement, but check the grid immediately above your post. The pivot (16) is in r9c1 and the others (14,46) are in r4c1 and r9c4.
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sheryl



Joined: 24 Sep 2007
Posts: 64
Location: New York

PostPosted: Wed Sep 01, 2010 4:21 pm    Post subject: thank you Reply with quote

it was right in front of me Rolling Eyes
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