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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Fri May 29, 2009 1:06 pm Post subject: Free Press May 29, 2009 |
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| Code: | Puzzle: FP052909
+-------+-------+-------+
| . . 6 | 2 . . | . . 7 |
| . 4 5 | . . . | . 6 . |
| . 9 1 | 4 . . | 5 . . |
+-------+-------+-------+
| . . . | . . 7 | 9 . . |
| 9 . . | . 8 . | . . 2 |
| . . 8 | 5 . . | . . . |
+-------+-------+-------+
| . . 3 | . . 5 | 2 4 . |
| . 8 . | . . . | 6 7 . |
| 5 . . | . . 9 | 8 . . |
+-------+-------+-------+ |
Keith |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Fri May 29, 2009 1:44 pm Post subject: freepress |
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Wow! I had to use an xy-chain and extend the (2) pincer.
Earl |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Fri May 29, 2009 2:18 pm Post subject: |
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| withdrawn -- bad thinking |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Fri May 29, 2009 3:29 pm Post subject: |
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Using basics, my solver reduces the puzzle to this PM before wanting to use a 4-cell XY-Chain. Not happy with that choice, I tackled it manually. What I see is a UR Type 2 that doesn't perform any eliminations. But, there is another UR present in the same cells because of strong links on <4> in [r6].
| Code: | <46> UR Type ??? [r46c19] => [r4c1]<>6
+-----------------------------------------------------+
| 8 3 6 | 2 5 1 | 4 9 7 |
| 2 4 5 | 9 7 8 | 13 6 13 |
| 7 9 1 | 4 3 6 | 5 2 8 |
|-----------------+-----------------+-----------------|
| 346 5 24 | 136 12 7 | 9 8 46 |
| 9 16 7 | 36 8 4 | 13 5 2 |
| 346 126 8 | 5 9 23 | 7 13 46 |
|-----------------+-----------------+-----------------|
| 16 7 3 | 8 16 5 | 2 4 9 |
| 14 8 9 | 13 124 23 | 6 7 5 |
| 5 26 24 | 7 46 9 | 8 13 13 |
+-----------------------------------------------------+
# 31 eliminations remain
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This is sufficient to expose an XY-Wing and a BUG+1 to complete the puzzle. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri May 29, 2009 3:57 pm Post subject: |
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After the hidden UR and XY-Wing, I'm here. As an alternative to the BUG, there's an XY-Wing Chain, 14-46-46-46-16.
| Code: |
+-----------+-----------+----------+
| 8 3 6 | 2 5 1 | 4 9 7 |
| 2 4 5 | 9 7 8 | 13 6 13 |
| 7 9 1 | 4 3 6 | 5 2 8 |
+-----------+-----------+----------+
| 3 5 24 | 16 12 7 | 9 8 46 |
| 9 16 7 | 36 8 4 | 13 5 2 |
| 46 12 8 | 5 9 23 | 7 13 46 |
+-----------+-----------+----------+
| 16 7 3 | 8 16 5 | 2 4 9 |
| 14 8 9 | 13 124 23 | 6 7 5 |
| 5 26 24 | 7 46 9 | 8 13 13 |
+-----------+-----------+----------+
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Play this puzzle online at the Daily Sudoku site |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Fri May 29, 2009 5:07 pm Post subject: |
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| Marty R. wrote: | As an alternative to the BUG, there's an XY-Wing Chain, 14-46-64-46-61.
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Why is this called an XY-Wing Chain 
I don't see any sign of an XY-Wing among groupings of three adjacent cells.
It appears to be a conventional XY-Chain with a truncated Remote Pair pattern for the middle three cells.
[Green: edited for clarity.] |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Fri May 29, 2009 5:13 pm Post subject: |
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After basics,
| Code: |
+--------------------------+--------------------------+--------------------------+
| 8 3 6 | 2 5 1 | 4 9 7 |
| 2 4 5 | 9 7 8 | 13 6 13 |
| 7 9 1 | 4 3 6 | 5 2 8 |
+--------------------------+--------------------------+--------------------------+
| 3-46 5 24* | 136 12# 7 | 9 8 46 |
| 9 16 7 | 36 8 4 | 13 5 2 |
| 3-46 126 8 | 5 9 23 | 7 13 46 |
+--------------------------+--------------------------+--------------------------+
| 16 7 3 | 8 16 5 | 2 4 9 |
| 14* 8 9 | 13 124# 23 | 6 7 5 |
| 5 26 2-4 | 7 46 9 | 8 13 13 |
+--------------------------+--------------------------+--------------------------+
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m-wing(4) r4c3=r8c1 [via (2) r4c5=r8c5]; r9c3,r4c1,r6c1 <> 4 |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat May 30, 2009 1:35 am Post subject: |
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| Quote: | | Why is this called an XY-Wing Chain |
I call it that because that's what the site that I learned it from called it.
| Quote: |
I don't see any sign of an XY-Wing among groupings of three adjacent cells.
It appears to be a conventional XY-Chain with a truncated Remote Pair pattern for the middle three cells. |
You're more of a theory guy than I am, but the three 46 cells work as if they were the XY cell of a conventional XY-Wing, with the 14 and 16 cells containing the pincers of 1.
| Quote: | | [Green: edited for clarity.] |
Danny, I have no idea what is being clarified here. |
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