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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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 Posted: Sat May 03, 2008 3:20 pm Post subject: May 3 vh |
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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
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| Posted: Sat May 03, 2008 4:18 pm Post subject: |
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| 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
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| Posted: Sat May 03, 2008 4:45 pm Post subject: |
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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
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| Posted: Sat May 03, 2008 4:51 pm Post subject: |
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| 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
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| Posted: Sat May 03, 2008 6:09 pm Post subject: |
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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 |
+------------+-------------+-------------+
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Play this puzzle online at the Daily Sudoku site |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Sat May 03, 2008 9:04 pm Post subject: |
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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
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| Posted: Sat May 03, 2008 9:16 pm Post subject: |
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| 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 |
+--------------------------+--------------------------+--------------------------+
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... at least I don't see any more basic moves in this grid  |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Sat May 03, 2008 9:42 pm Post subject: |
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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
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| Posted: Sun May 04, 2008 1:23 am Post subject: |
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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
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| Posted: Sun May 04, 2008 2:00 pm Post subject: |
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| 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 |
'------------------'------------------'------------------' |
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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  |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Sun May 04, 2008 3:38 pm Post subject: |
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| tlanglet wrote: | I originally did not see the second wing and I suspect that you did not notice the one I used.
Ted |
You described it perfectly, Ted. I used the same wing Norm did and kept wondering what other wing people were talking about... 
Thanks ! |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Sun May 04, 2008 8:07 pm Post subject: |
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wow 
and I didn't see the multicoloring on 1's |
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