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Help on a real hard puzzle

 
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Captain Pete



Joined: 09 Jun 2007
Posts: 55
Location: Oley, PA

PostPosted: Mon Sep 17, 2007 11:57 am    Post subject: Help on a real hard puzzle Reply with quote

I'm stuck here. Any ideas?

Code:

+-------+-------+-------+
| 2 5 1 | 9 8 3 | 7 6 4 |
| . . 8 | 5 . . | 3 2 9 |
| . . 3 | . 2 7 | . 1 . |
+-------+-------+-------+
| 3 4 6 | 1 9 8 | 2 5 7 |
| . . . | . 5 . | . . . |
| . . 5 | . . 2 | . . 6 |
+-------+-------+-------+
| . 3 . | . 4 5 | . . . |
| . 8 4 | 2 . . | . . . |
| 5 . . | . . 9 | 6 4 . |
+-------+-------+-------+
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Captain Pete



Joined: 09 Jun 2007
Posts: 55
Location: Oley, PA

PostPosted: Mon Sep 17, 2007 12:25 pm    Post subject: Sorry - Additional number Reply with quote

C1R6 is an 8. I missed that on my previous post

Code:

+-------+-------+-------+
| 2 5 1 | 9 8 3 | 7 6 4 |
| . . 8 | 5 . . | 3 2 9 |
| . . 3 | . 2 7 | . 1 . |
+-------+-------+-------+
| 3 4 6 | 1 9 8 | 2 5 7 |
| . . . | . 5 . | . . . |
| 8 . 5 | . . 2 | . . 6 |
+-------+-------+-------+
| . 3 . | . 4 5 | . . . |
| . 8 4 | 2 . . | . . . |
| 5 . . | . . 9 | 6 4 . |
+-------+-------+-------+
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Steve R



Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England

PostPosted: Mon Sep 17, 2007 6:13 pm    Post subject: Reply with quote

You can advance using the wxyz-wing pivoted on r5c4 with pincers r6c4, r6c5 and r3c4. I think two more eliminations based on almost locked sets will then bring you to an easy ride home.

Steve
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Mon Sep 17, 2007 8:30 pm    Post subject: Reply with quote

Steve,

I've probably misread your diagram but doesn't the Z cell have to be seen by all the others ?
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keith



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

PostPosted: Mon Sep 17, 2007 11:59 pm    Post subject: Reply with quote

With candidates:
Code:

GRID 1
+----------------+----------------+----------------+
| 2    5    1    | 9    8    3    | 7    6    4    |
| 47   67   8    | 5    16   146  | 3    2    9    |
| 49   69   3    | 46   2    7    | 58   1    58   |
+----------------+----------------+----------------+
| 3    4    6    | 1    9    8    | 2    5    7    |
| 179  1279 279  | 3467 5    46   | 1489 389  138  |
| 8    179  5    | 347  37   2    | 149  39   6    |
+----------------+----------------+----------------+
| 1679 3    279  | 678  4    5    | 189  789  128  |
| 1679 8    4    | 2    1367 16   | 159  379  135  |
| 5    127  27   | 378  137  9    | 6    4    1238 |
+----------------+----------------+----------------+

There is a <16> UR in R28C56. With the strong links on <1> and <6>, R8C5 is not <1>, R2C6 is not <6>.

Then, an XY-wing takes out <6> in R7C4, leaving:

Code:

GRID 2
+----------------+----------------+----------------+
| 2    5    1    | 9    8    3    | 7    6    4    |
| 47   67   8    | 5    16   14   | 3    2    9    |
| 49   69   3    | 46   2    7    | 58   1    58   |
+----------------+----------------+----------------+
| 3    4    6    | 1    9    8    | 2    5    7    |
| 179  1279 279  | 3467 5    46   | 1489 389  138  |
| 8    179  5    | 347  37   2    | 149  39   6    |
+----------------+----------------+----------------+
| 6    3    279  | 78   4    5    | 189  789  128  |
| 179  8    4    | 2    367  16   | 59   379  35   |
| 5    127  27   | 378  137  9    | 6    4    238  |
+----------------+----------------+----------------+


Still working on it ...

Keith
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Tue Sep 18, 2007 12:33 am    Post subject: Reply with quote

I got to the same place as Keith slightly differently. I Medusa colored {16} in those UR cells, which eliminated the <6>s in R7C4 and R8C1. After that, I still had to do the UR eliminations.
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Steve R



Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England

PostPosted: Tue Sep 18, 2007 12:44 am    Post subject: Reply with quote

MM

Starting from Keith’s GRID 1 I think the wing I mentioned eliminates 6 from r7c4. As a consequence 1 is eliminated from r9c9.

Next came the almost locked sets r3c24 and r6c458. Finally, r6c25 and r9c2349 finish the work.

Steve
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Tue Sep 18, 2007 1:44 am    Post subject: Reply with quote

Steve,

I don't really see how your first wing eliminates that <6>. But, as already noted, there are other ways to eliminate it.

I saw the <9> elimination in R6C2 as the result of an ALS Chain, which is basically the same as your rather more elegant ALS.

I don't see how your final ALS involving the 4 cells in R9 works. I can see a shared exclusive of <1> but can't see a shared common that results in eliminations.

However, at this point in the puzzle, I noticed something that I found interesting involving, yes, Medusa coloring again!
Code:
+------------------+------------------+------------------+
| 2     5     1    | 9     8     3    | 7     6     4    |
| 4r7g  6g7r  8    | 5     1g6r  1r4g | 3     2     9    |
| 4g9r  6r9g  3    | 4r6g  2     7    | 58    1     58   |
+------------------+------------------+------------------+
| 3     4     6    | 1     9     8    | 2     5     7    |
| 1g79  1279  279  | 346r7 5     4r6g | 148   38    138  |
| 8     17    5    | 347   37    2    | 149   39    6    |
+------------------+------------------+------------------+
| 6     3     279  | 78    4     5    | 189   789   128  |
| 1r79  8     4    | 2     36g7  1g6r | 59    379   35   |
| 5     1g27  27   | 378   1r37  9    | 6     4     238  |
+------------------+------------------+------------------+

Note that C2 contains a "red" <7> and a "green" <1> and an uncolored {17} bivalue cell. The other <1>s and <7>s can be removed from this column (i.e. <1> and <7> in R5C2 and <7> in R9C2).
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Tue Sep 18, 2007 2:20 am    Post subject: Reply with quote

PS:

I see how that first ALS "wing" works now to eliminate the <6>.
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