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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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 Posted: Wed Jul 04, 2007 2:11 pm Post subject: Stuck Again |
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I can solve this with a forcing chain to a contradiction, which is almost trial and error. Anyone see a "logical" step?
Thanks
Earl
| Code: |
+------------+-------+------------+
| 16 9 168 | 3 5 7 | 68 2 4 |
| 4 3 2 | 1 8 6 | 9 7 5 |
| 5 67 78 | 9 4 2 | 38 36 1 |
+------------+-------+------------+
| 3 8 16 | 5 7 4 | 16 9 2 |
| 17 56 1457 | 8 2 9 | 1347 36 37 |
| 9 2 47 | 6 1 3 | 47 5 8 |
+------------+-------+------------+
| 2 57 9 | 4 3 8 | 57 1 6 |
| 8 1 3 | 7 6 5 | 2 4 9 |
| 67 4 567 | 2 9 1 | 357 8 37 |
+------------+-------+------------+
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Play this puzzle online at the Daily Sudoku site |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Jul 04, 2007 3:54 pm Post subject: Re: Stuck Again |
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| Earl wrote: | I can solve this with a forcing chain to a contradiction, which is almost trial and error. Anyone see a "logical" step?
Thanks
Earl
| Code: |
+------------+-------+------------+
| 16 9 168 | 3 5 7 | 68 2 4 |
| 4 3 2 | 1 8 6 | 9 7 5 |
| 5 67 78 | 9 4 2 | 38 36 1 |
+------------+-------+------------+
| 3 8 16 | 5 7 4 | 16 9 2 |
| 17 56 1457 | 8 2 9 | 1347 36 37 |
| 9 2 47 | 6 1 3 | 47 5 8 |
+------------+-------+------------+
| 2 57 9 | 4 3 8 | 57 1 6 |
| 8 1 3 | 7 6 5 | 2 4 9 |
| 67 4 567 | 2 9 1 | 357 8 37 |
+------------+-------+------------+
|
Play this puzzle online at the Daily Sudoku site |
There is a Type 4 rectangle on 47 in boxes 4 and 6 which I don't know if it does any good. But there's an XY-Wing 17-16-67 which will accomplish something, but I don't know if it breaks the puzzle. |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Wed Jul 04, 2007 7:50 pm Post subject: |
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There is a W-Wing on 16 in Boxes 1 and 4.
Or, there is an XY-Chain with pincers at R4C7 and R5C1 that eliminates <1> from R5C7. |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Wed Jul 04, 2007 8:36 pm Post subject: |
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| There's also an X-wing/swordfish that removes >7> from r9c3, after which the XY-wing that Marty mentioned solves that same cell. |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Wed Jul 04, 2007 11:47 pm Post subject: |
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Picking up on Tracy's x-wing on 7's that removes the 7 from r9c3 (and a bunch of other 7's) This leaves a Y wing at r3c2 r7c2 r9c3 , (67-57-56)
............which knocks out the 6 at r1c3.
Another Y wing straight afterwards at r1c37 and r4c3 chops out yet another 6 and the puzzle is toast. |
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