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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Sat Sep 01, 2007 3:16 pm Post subject: DB Saturday Puzzle: September 1, 2007 |
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| Code: | Puzzle: DB090107 ******
+-------+-------+-------+
| 2 . . | . . . | . . . |
| 4 . . | 8 . 6 | . 3 . |
| 8 9 . | . 3 1 | . . . |
+-------+-------+-------+
| . . 4 | . 1 9 | 2 . 8 |
| . . . | . . . | . . . |
| 5 . 9 | 7 8 . | 1 . . |
+-------+-------+-------+
| . . . | 1 5 . | . 2 7 |
| . 7 . | 3 . 8 | . . 6 |
| . . . | . . . | . . 9 |
+-------+-------+-------+ |
An easy W-wing is one way ...
Keith |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Sat Sep 01, 2007 3:57 pm Post subject: Sept 1 DB |
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Also an xy-wing eliminates 2 from R2C5, and opens the puzzle.
Earl |
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sdq_pete
Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL
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| Posted: Sat Sep 01, 2007 4:28 pm Post subject: |
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I saw the other XY wing, eliminating 2 also from R5C5 (pivot at R1C6):
| Code: |
+-----------+-----------+------------+
| 2 156 3 | 9 4 57 | 67 8 15 |
| 4 15 17 | 8 27 6 | 9 3 125 |
| 8 9 67 | 25 3 1 | 467 47 25 |
+-----------+-----------+------------+
| 67 3 4 | 56 1 9 | 2 57 8 |
| 67 18 18 | 4 26 25 | 57 9 3 |
| 5 2 9 | 7 8 3 | 1 6 4 |
+-----------+-----------+------------+
| 9 68 68 | 1 5 4 | 3 2 7 |
| 1 7 2 | 3 9 8 | 45 45 6 |
| 3 4 5 | 26 267 27 | 8 1 9 |
+-----------+-----------+------------+
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Play this puzzle online at the Daily Sudoku site
Peter |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Sep 01, 2007 4:42 pm Post subject: |
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| I missed the W, but the one XY did it. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Sep 01, 2007 5:32 pm Post subject: |
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| Marty R. wrote: | | I missed the W ... |
Look at <26> in C45, connected by strong link on <2> in B2. Takes out <6> in R9C5.
Keith |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Sat Sep 01, 2007 11:09 pm Post subject: |
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I missed the xy- wing, but found a 4-cell xy-chain
Starting with <6> in R4C4 => R9C4=2 => R9C6=7 => R1C6=5, resulting in two <5> pincer cells in R4C4 and R1C6, eliminating both <5>'s in R5C6 and R3C4(both can see the <5> pincer cells)
[56][62][27][75] |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Sat Sep 01, 2007 11:39 pm Post subject: |
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As an interesting alternative to the single XY Wing solution...
Note the {15} UR in R12C29. There is a <5> strong link in C2 and a <1> strong link in C9. Thus, <1> is removed from R1C2 and 5 is removed from R2C9. |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Sun Sep 02, 2007 12:39 am Post subject: |
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Asellus,
I followed a diffirent solving path for the [15] UR you mentioned.
For avoiding the deadly [15] pattern in R12C29.
R1C2 must be <6> or R2C9 must be <2>.
Presume that R2C9=2 => R2C5=7 => R1C6=5 => R1C9=1
=> R1C2=6, which means that <6> can only reside in R1C2, logical thinking(or did I make a lucky guess)?
Because <6> acts like a pincer cell, starting with <2> in R2C9 ends up with <6> in R1C2, which pins the <6> in R1C2. |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Sun Sep 02, 2007 7:45 pm Post subject: |
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| Johan wrote: | | logical thinking(or did I make a lucky guess)? |
Your logic is fine: either candidate for avoiding the DP forces the other. |
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