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Competition diabolical #1230 Nov 21

 
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Fri Nov 21, 2008 4:24 pm    Post subject: Competition diabolical #1230 Nov 21 Reply with quote

Today's Diabolical

Code:

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


play online
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Fri Nov 21, 2008 4:34 pm    Post subject: Reply with quote

It starts off with an m-wing:
Code:

+--------------------------+--------------------------+--------------------------+
| 8       57#     6        | 13      9       35*      | 2       17#     4        |
| 257     9       1257     | 168     4      -56       | 57*     3       78       |
| 35      4       135      | 7       58      2        | 569     169     89       |
+--------------------------+--------------------------+--------------------------+
| 1       37      379      | 2       6       8        | 4       79      5        |
| 6       2       79       | 5       3       4        | 1       8       79       |
| 4       58      58       | 9       7       1        | 3       2       6        |
+--------------------------+--------------------------+--------------------------+
| 239     368     238      | 4       1       7        | 69      5       23       |
| 23579   1       2357     | 368     58      3569     | 679     4       23       |
| 3579    3567    4        | 36      2       3569     | 8       679     1        |
+--------------------------+--------------------------+--------------------------+


m-wing (5)r2c7=r1c6 (via SL (7) in row 1), removes 5 from r2c6.

With 6 gone from r2c4, there is now an xy-wing 17-78-18 box 3/row 2 and the puzzle is solved. Very enjoyable. Very Happy
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri Nov 21, 2008 6:30 pm    Post subject: Reply with quote

I thought so too. nothing stood out so a careful inspection was needed.
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Fri Nov 21, 2008 9:29 pm    Post subject: Sir cgordon Reply with quote

Today is undoubtably my finest hour. Although I haven't yet grasped Nataraj's weak-strong-weak Grouped Multi Coloring concept (explained in today's V. Fiendish post) - I did continue with my brilliant strong link method (BS).
Thus there is a strong link for 5 in R1. The right one uses an ER in Box8 to remove <5> in R8C3. The left one uses a transport in B4 to do the same. And it's exactly the same thing for the strong link <7> in R1 for removing the <7> in R8C3.
This leaves a Type 2 UR and then a Type 4 UR in the same cells (R78C3).

If the Queen does Sudokus and checks out this Forum, I'm a shoe-in for the Honours List.
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Fri Nov 21, 2008 9:46 pm    Post subject: Reply with quote

Quote:
I did continue with my brilliant strong link method (BS).

Oh what a brilliant acronym for your method, Craig. Laughing Laughing
Definitely needs to be trademarked ASAP.

Seriously, the method is quite good. Seeing how you spot the ERs first, I'd simply call that an ER with transport.

P.S. The confusing thing with ERs is that the same name "empty rectangle" denotes both a pattern within a box (which is simply a grouped strong link, in box 8 ) and a larger pattern where that "hinge" is combined with a strong link to provide the elimination.

What we have here is the same situation as with a "useless xy-wing": there is no cell with "5" that sees both ends of the "large" ER (r1c2, r8c5), but one of the ends of that ER can be transported (to r6c3) and now the "5" in r8c3 is toast.
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