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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Wed Jan 02, 2008 2:55 am Post subject: Happy New Year! - One from Carcul |
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I found this posted in a couple of places on another forum:
| Code: | . . . | . . . | . . .
. 9 . | 8 . 5 | . 4 .
. . 6 | . 7 . | 8 . .
-------+-------+------
. 5 . | . . . | . 3 .
. . 1 | . 8 . | 6 . .
. 4 . | . . . | . 2 .
-------+-------+------
. . 2 | . 6 . | 7 . .
. 6 . | 1 . 9 | . 5 .
. . . | . . . | . . . |
http://www.sudoku.com/boards/viewtopic.php?t=2575
Take your time!
Best wishes,
Keith |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Wed Jan 02, 2008 6:25 am Post subject: |
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| Code: | 1 8 45 | 2 349 6 | 359 7 359
7 9 3 | 8 1 5 | 2 4 6
45 2 6 | 349 7 34 | 8 1 359
------------------------+-------------------------+------------------
2 5 89 | 6 49 17 | 14 3 78
3 7 1 | 45 8 2 | 6 9 45
6 4 89 | 359 359 17 | 15 2 78
------------------------+-------------------------+------------------
459 13 2 | 345 6 34 | 7 8 1349
8 6 7 | 1 234 9 | 34 5 234
459 13 45 | 7 2345 8 | 349 6 12349
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Wed Jan 02, 2008 6:58 am Post subject: |
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| so is that a UR on 13 in rows 7 and 9?? taking out the 3's in r7c9 and r9c9?? |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Wed Jan 02, 2008 7:12 am Post subject: |
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| finned x-wing on 4 takes out 4 in r9c7 |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Wed Jan 02, 2008 7:53 am Post subject: |
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if you color 5,
you will see three sets of conjugate 5's in rows 3,5,7
and nice enough, you can see the same pattern if you look to the verticle.
the conjugate pairs of 5's in columns 3,5,7
all doing the same thing. forming a swordfish pattern and killing the 5's in
r9c1
r6c4
r1c9
looking for xy-chains tomorrow |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Wed Jan 02, 2008 1:05 pm Post subject: |
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There is a potential [34] DP* in R37C46, for avoiding that DP either R7C4=5 or R3C4=9 or both
When R7C4=5 => R5C4=4 => R4C5=9 => R3C4=9, which pins <9> in R3C4, after that, pincer colouring(r=true
g=false) on the idle [34-35-45] xy-wing@ takes out <4> in R1C4, solving the puzzle.
| Code: |
+--------------------------+--------------------------+--------------------------+
| 1 5 45 | 2 34g-[9] 6 | 359 7 359 |
| 7 9 3 | 8 1 5 | 2 4 6 |
| 45 2 6 |*349 [=9] 7 @ 34r *| 8 1 @ 35-[9]|
+--------------------------+--------------------------+--------------------------+
| 2 5 89 | 6 49r 17 | 14g 3 78 |
| 3 7 1 | 45 8 2 | 6 9 @ 45r |
| 6 4 89 | 359 359 17 | 15 2 78 |
+--------------------------+--------------------------+--------------------------+
| 459 13 2 |*345 6 34 *| 7 8 1349 |
| 8 6 7 | 1 234 9 | 34 5 234 |
| 459 13 45 | 7 2345 8 | 349 6 12349 |
+--------------------------+--------------------------+--------------------------+ |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Wed Jan 02, 2008 1:41 pm Post subject: |
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Many ways to solve it. First i started from storm_norms grid, also noticed the UR 34 to eliminate 9 from r1c5. Then i used 3 strong links to eliminate 5 from r6c4 (only later i saw that there is a swordfish), which gave me a 4-cell xy-chain to eliminate 5 from r7c1.
But i know, that Carcul likes 1-step-solutions, so i restarted and applied the swordfish first:
| Code: | *--------------------------------------------------------------------*
| 1 8 A45 | 2 3-49 6 | 359 7 39 |
| 7 9 3 | 8 1 5 | 2 4 6 |
|B45 2 6 | 3-49 7 34 | 8 1 E359 |
|----------------------+----------------------+----------------------|
| 2 5 89 | 6 -49 17 | 14 3 78 |
| 3 7 1 |C45 8 2 | 6 9 D45 |
| 6 4 89 | 39 359 17 | 15 2 78 |
|----------------------+----------------------+----------------------|
| 459 13 2 | 345 6 34 | 7 8 1349 |
| 8 6 7 | 1 234 9 | 34 5 234 |
| 49 13 45 | 7 2345 8 | 349 6 12349 |
*--------------------------------------------------------------------*
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Now i concentrated on the 45's. There is a strong link for 5 in column 9 ED, which builds a w-wing with BC and eliminates 4 in r3c4. But it does not help much.
With the strong link for 5 in row 3 B and D are complementary pairs (either both are 4 or both are 5), but i could not find a strong link to make another elimination. But then A and C are complementary pairs also. With the strong link for 4 in row 1 one of r1c5 or C must be 4 => r4c5<>4 and r3c4<>4. With the link in box 5 one of A and r4c5 must be 4 => r1c5<>4.
The rest are singles. |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Wed Jan 02, 2008 2:49 pm Post subject: |
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| There is a typo in my previous post, <4> in R1C4, must be <4> in R1C5 |
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