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Happy New Year! - One from Carcul

 
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Wed Jan 02, 2008 2:55 am    Post subject: Happy New Year! - One from Carcul Reply with quote

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

PostPosted: Wed Jan 02, 2008 6:25 am    Post subject: Reply with quote

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

PostPosted: Wed Jan 02, 2008 6:58 am    Post subject: Reply with quote

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

PostPosted: Wed Jan 02, 2008 7:12 am    Post subject: Reply with quote

finned x-wing on 4 takes out 4 in r9c7
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed Jan 02, 2008 7:53 am    Post subject: Reply with quote

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

PostPosted: Wed Jan 02, 2008 1:05 pm    Post subject: Reply with quote

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

PostPosted: Wed Jan 02, 2008 1:41 pm    Post subject: Reply with quote

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  |
 *--------------------------------------------------------------------*
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

PostPosted: Wed Jan 02, 2008 2:49 pm    Post subject: Reply with quote

There is a typo in my previous post, <4> in R1C4, must be <4> in R1C5
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