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Yesterday's BB sh

 
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keith



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

PostPosted: Fri Dec 19, 2008 9:52 pm    Post subject: Yesterday's BB sh Reply with quote

Just a touch more than this site's Very Hard:
Code:
Puzzle: BB121808sh
+-------+-------+-------+
| 1 . . | . 2 . | . . 4 |
| . . 8 | 3 . 9 | 5 . . |
| . 2 . | . . . | . 8 . |
+-------+-------+-------+
| . 9 . | . 8 . | . 1 . |
| 8 . . | 6 . 7 | . . 9 |
| . 5 . | . 3 . | . 7 . |
+-------+-------+-------+
| . 7 . | . . . | . 5 . |
| . . 5 | 4 . 2 | 6 . . |
| 2 . . | . 9 . | . . 7 |
+-------+-------+-------+


Keith
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri Dec 19, 2008 10:14 pm    Post subject: Reply with quote

Quote:
w-wing 18
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keith



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

PostPosted: Fri Dec 19, 2008 10:24 pm    Post subject: Reply with quote

storm_norm wrote:
Quote:
w-wing 18
I did not see that! There are at least three other "advanced" moves. After "basics":
Code:
+----------------+----------------+----------------+
| 1    36   369  | 58   2    58   | 7    369  4    |
| 7    46   8    | 3    14   9    | 5    26   12   |
| 5    2    349  | 7    14   6    | 19   8    13   |
+----------------+----------------+----------------+
| 6    9    7    | 2    8    4    | 3    1    5    |
| 8    13   13   | 6    5    7    | 24   24   9    |
| 4    5    2    | 9    3    1    | 8    7    6    |
+----------------+----------------+----------------+
| 39   7    14   | 18   6    38   | 1249 5    1238 |
| 39   18   5    | 4    7    2    | 6    39   18   |
| 2    1468 146  | 158  9    358  | 14   34   7    |
+----------------+----------------+----------------+
Keith
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Fri Dec 19, 2008 10:46 pm    Post subject: Reply with quote

Besides XY-Chains, did you see this companion to Norm's solution?

Quote:
W-Wing <14> in Band 3 => [r7c7],[r9c23]<>4
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Fri Dec 19, 2008 11:11 pm    Post subject: Reply with quote

Another one-stepper:
Quote:
UR <58> r19c46. Pseudo-cell <13> from UR & r9c78 gives subset <134>; delete <14> in r9c23

Ted
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keith



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

PostPosted: Sat Dec 20, 2008 12:09 am    Post subject: Reply with quote

The <14> W-wing with 3 eliminations is really cool.

Yes, I saw the UR elimination on pencil & paper. Is it a one-stepper?

The way I solved it (P&P), after the UR, was with a pseudo-cell to create an extended XY-wing.
Code:
+----------------+----------------+----------------+
| 1    36   369  | 58   2    58   | 7   36-9  4    |
| 7    46   8    | 3    14   9    | 5    26   12   |
| 5    2    349  | 7    14   6    | 19a  8    13   |
+----------------+----------------+----------------+
| 6    9    7    | 2    8    4    | 3    1    5    |
| 8    13   13   | 6    5    7    | 24   24   9    |
| 4    5    2    | 9    3    1    | 8    7    6    |
+----------------+----------------+----------------+
| 39   7    14   | 18   6    38   | 1249 5    1238 |
| 39   18   5    | 4    7    2    | 6    39d  18   |
| 2    1468 146  | 158  9    358  | 14b  34c  7    |
+----------------+----------------+----------------+


There are so many bi-value cells, there must be something! Look at R89C8, c and d; <39> and <34> means that these two cells contain one of <49>. So a b cd is an extended XY-wing that takes out <9> in R1C8, solving the puzzle.

I have taken to looking for these before I look for the possible pairs and strong links that might make skyscrapers, W-wings, etc.

Keith
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cgordon



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

PostPosted: Sat Dec 20, 2008 1:54 pm    Post subject: Reply with quote

I am of course a heavy user of w-wings (since I learnt about them this week). After a Type 4 UR (58) there were w -wings on 14 and 18.
(I think).
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