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May 3 vh

 
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nataraj



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

PostPosted: Sat May 03, 2008 3:20 pm    Post subject: May 3 vh Reply with quote

two-step:

x-wing (6) cols 4,9; then
xy-wing 17-47-14 boxes 2,8
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Victor



Joined: 29 Sep 2005
Posts: 207
Location: NI

PostPosted: Sat May 03, 2008 4:18 pm    Post subject: Reply with quote

Sorry, silly of me. I've changed my title.
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Marty R.



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

PostPosted: Sat May 03, 2008 4:45 pm    Post subject: Reply with quote

Quote:
two-step:

Five-step.

I tend to look for X-Wings only after I've exhausted other methods. So on this one it was an M-Wing on 17, XY-Wing on 894, UR on 69, then the X-Wing on 6, followed by the finishing 471 XY-Wing.
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Johan



Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium

PostPosted: Sat May 03, 2008 4:51 pm    Post subject: Reply with quote

I used the 69 UR in R58C79, which eliminates both <6>'s in R58C7 (there is an x-wing on <9> in the 69 UR, placing <6> in either R5C7 or in R8C7 results in a 69 DP), then M-wing on the {17} pair eliminating <1> in R456C5, finally the x-wing on <6> solved the puzzle for me
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crunched



Joined: 05 Feb 2008
Posts: 168

PostPosted: Sat May 03, 2008 6:09 pm    Post subject: Reply with quote

I post the puzzle, after (most or all) basics removed.
Code:

+------------+-------------+-------------+
| 6  249 3   | 17  14   5  | 2479 249 8  |
| 48 1   28  | 9   3    78 | 2467 246 5  |
| 5  7   89  | 2   48   6  | 3    49  1  |
+------------+-------------+-------------+
| 7  8   16  | 3   1256 9  | 1256 126 4  |
| 3  5   4   | 167 126  17 | 1269 8   69 |
| 2  69  169 | 4   1568 18 | 1569 7   3  |
+------------+-------------+-------------+
| 1  46  5   | 8   9    2  | 46   3   7  |
| 48 246 268 | 16  7    3  | 1469 5   69 |
| 9  3   7   | 5   16   4  | 8    16  2  |
+------------+-------------+-------------+

Play this puzzle online at the Daily Sudoku site
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cgordon



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

PostPosted: Sat May 03, 2008 9:04 pm    Post subject: Reply with quote

Which post do I go to with this one? Pls. maintain one post related to one sudoku - or I will get very cross. ... Just as I got cross with this one.

I had to do this one 3 times.

I eventually solved everything based on x-wings for <6> - nothing else.

If the solution for this one is truly based on nothing more than x-wings on <6> - it should be demonstrated as a classic example of a complex VH that can be solved by the most simplistic of VH methods.

Am I right ?
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nataraj



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

PostPosted: Sat May 03, 2008 9:16 pm    Post subject: Reply with quote

cgordon wrote:
I eventually solved everything based on x-wings for <6> - nothing else.

If ... Am I right ?


I don't think so.
It happens near the end. But there is a point where the x-wing alone is not enough. After the x-wing on 6 and even after (multi-) coloring on 1, this is where at least an xy-wing if not harsher means become necessary:

Code:

+--------------------------+--------------------------+--------------------------+
| 6       24      3        | 17      14      5        | 27      9       8        |
| 48      1       28       | 9       3       47       | 267     26      5        |
| 5       7       9        | 2       8       6        | 3       4       1        |
+--------------------------+--------------------------+--------------------------+
| 7       8       16       | 3       256     9        | 1256    126     4        |
| 3       5       4        | 167     12      17       | 29      8       69       |
| 2       9       16       | 4       56      8        | 156     7       3        |
+--------------------------+--------------------------+--------------------------+
| 1       6       5        | 8       9       2        | 4       3       7        |
| 48      24      28       | 16      7       3        | 19      5       69       |
| 9       3       7        | 5       146     14       | 8       16      2        |
+--------------------------+--------------------------+--------------------------+


... at least I don't see any more basic moves in this grid Smile
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sat May 03, 2008 9:42 pm    Post subject: Reply with quote

just copied this over here from the other thread.

this is my position along my path, and where I found the marked x-wing on 6.
that x-wing opens up some naked pairs, etc...
which opened up the xy-wing as mentioned on {1,4,7} in boxes 2 and 8. but my xy-wing eliminated a 1 in r8c4

Code:
.------------------.------------------.------------------.
| 6     249   239  | 17    14    5    | 2347  249   8    |
| 48    1     28   | 9     3     478  | 2467  246   5    |
| 5     7     389  | 2     48    6    | 34    49    1    |
:------------------+------------------+------------------:
| 7     8     16   | 3     1256  9    | 1256  126   4    |
| 3     5     4    |#167   126   127  | 1269  8    #69   |
| 2     69    169  | 4     1568  18   | 156   7     3    |
:------------------+------------------+------------------:
| 1     246   5    | 8     9     24   | 46    3     7    |
| 48    246   268  |#16    7     3    | 1469  5    #69   |
| 9     3     7    | 5     146   14   | 8     146   2    |
'------------------'------------------'------------------'
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cgordon



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

PostPosted: Sun May 04, 2008 1:23 am    Post subject: Reply with quote

Quote:
I don't think so.

Think you're right.
Started it again (4th time) - this sudoku and me aint compatible. I found the xy wing but am still struggling. I'll resume tomorrow after the 19th hole.
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tlanglet



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

PostPosted: Sun May 04, 2008 2:00 pm    Post subject: Reply with quote

storm_norm wrote:
just copied this over here from the other thread.

this is my position along my path, and where I found the marked x-wing on 6.
that x-wing opens up some naked pairs, etc...
which opened up the xy-wing as mentioned on {1,4,7} in boxes 2 and 8. but my xy-wing eliminated a 1 in r8c4

Code:
.------------------.------------------.------------------.
| 6     249   239  | 17    14    5    | 2347  249   8    |
| 48    1     28   | 9     3     478  | 2467  246   5    |
| 5     7     389  | 2     48    6    | 34    49    1    |
:------------------+------------------+------------------:
| 7     8     16   | 3     1256  9    | 1256  126   4    |
| 3     5     4    |#167   126   127  | 1269  8    #69   |
| 2     69    169  | 4     1568  18   | 156   7     3    |
:------------------+------------------+------------------:
| 1     246   5    | 8     9     24   | 46    3     7    |
| 48    246   268  |#16    7     3    | 1469  5    #69   |
| 9     3     7    | 5     146   14   | 8     146   2    |
'------------------'------------------'------------------'


Norm,

This is a very interesting xy-wing circumstances! We have two different xy-wings using a common pivot cell: the <47> at r2c6. I believe that you used the pincers <17> at r1c4 and <14> at r9c6, which deletes <1> at r8c4. I used the same pivot cell but used pincers <14> at r1c5 and <17> at r5c6 which deletes <1> from r46c5.

I originally did not see the second wing and I suspect that you did not notice the one I used.

Ted Rolling Eyes
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nataraj



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

PostPosted: Sun May 04, 2008 3:38 pm    Post subject: Reply with quote

tlanglet wrote:
I originally did not see the second wing and I suspect that you did not notice the one I used.

Ted Rolling Eyes


You described it perfectly, Ted. I used the same wing Norm did and kept wondering what other wing people were talking about... Shocked
Thanks !
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sun May 04, 2008 8:07 pm    Post subject: Reply with quote

wow Laughing

and I didn't see the multicoloring on 1's
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