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Puzzle BBDB_002

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed May 27, 2009 4:12 pm    Post subject: Puzzle BBDB_002 Reply with quote

This is a mini-BBDB, but don't let that mislead you.

No chains/extensions/transports allowed.

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

Play this puzzle online at the Daily Sudoku site
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed May 27, 2009 6:04 pm    Post subject: Reply with quote

if anyone else's last step is a pseudo cell xy-wing (a.k.a. 4 cell xy-chain), then we may have an identical solution path.
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed May 27, 2009 8:31 pm    Post subject: Reply with quote

Hint wrote:
If you don't find the doubly-grouped 2-String Kite, then you will probably never find the final W-Wing.

BTW: I consider a pseudo-cell to be an extension.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed May 27, 2009 8:47 pm    Post subject: Reply with quote

Quote:
BTW: I consider a pseudo-cell to be an extension.

noted.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed May 27, 2009 9:07 pm    Post subject: Reply with quote

without extensions...

Code:
.------------------------.------------------------.------------------------.
| 8      *345    *345    |*35      1       9      | 2       6       7      |
|*57      1       269    | 56      2568    25678  | 3       4       59     |
|*357     29      269    | 3456    2456    234567 | 8       59      1      |
:------------------------+------------------------+------------------------:
|*35      7       345    | 3456    9       1      | 56      2       8      |
| 6       4589    4589   | 2       7       45     | 1       3       459    |
| 1       23459   23459  | 8       456     3456   | 569     7       459    |
:------------------------+------------------------+------------------------:
| 2       58      1      | 9       46      46     | 7       58      3      |
| 4       6       7      | 1       3       58     | 59      589     2      |
| 9       358     358    | 7       258     258    | 4       1       6      |
'------------------------'------------------------'------------------------'

either you can view the marked cells above as w-wings on both 3 and 5 (both with grouped strong links)
or you can see them as grouped linked kites on 3 and 5.
either way, you can remove the 3 and 5 from r4c4

followed by a xy-wing that removes 5 from r5c9
leads to this grid in which the removal of that 5 provides the conjugate link on 5's in col 9 needed to complete Danny's hint.
Code:
.------------------.------------------.------------------.
| 8     345   345  | 35    1     9    | 2     6     7    |
| 57    1     269  | 56    268   2678 | 3     4     59   |
| 357   29    269  | 3456  246   2467 | 8     59    1    |
:------------------+------------------+------------------:
| 35    7     345  | 46    9     1    | 56    2     8    |
| 6     4589  4589 | 2     7     45   | 1     3     49   |
| 1     2459  2459 | 8     456   3    | 569   7     459  |
:------------------+------------------+------------------:
| 2     58    1    | 9     46    46   | 7     58    3    |
| 4     6     7    | 1     3     58   | 59    589   2    |
| 9     358   358  | 7     258   258  | 4     1     6    |
'------------------'------------------'------------------'
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed May 27, 2009 11:40 pm    Post subject: Reply with quote

Congratulations Norm. You reduced the puzzle to the shortest solution that I'm aware exists.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed May 27, 2009 11:48 pm    Post subject: Reply with quote

daj95376 wrote:
Congratulations Norm. You reduced the puzzle to the shortest solution that I'm aware exists.

Idea
this isn't the solution you were hinting at?
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tlanglet



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

PostPosted: Thu May 28, 2009 12:22 am    Post subject: Reply with quote

I had a four step solution which, after reading the existing posts, are similar.

ER3 with hinge in box2 and strong link in col1 deletes 3 from r4c4,
w-wing 35 deletes 5 in r4c4,
xy-wing 456 with pivot 46 deletes 5 from r5c9,
w-wing 56 deletes 6 from r4c4.

Ted
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Thu May 28, 2009 4:39 am    Post subject: Reply with quote

tlanglet wrote:
I had a four step solution which, after reading the existing posts, are similar.

ER3 with hinge in box2 and strong link in col1 deletes 3 from r4c4,
w-wing 35 deletes 5 in r4c4,
xy-wing 456 with pivot 46 deletes 5 from r5c9,
w-wing 56 deletes 6 from r4c4.

Ted

Mine was identical to Ted's, except I also played an ER on 9 in addition to the one on 3.
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Thu May 28, 2009 4:59 am    Post subject: Reply with quote

Here is the solution from my solver, which I've annotated. It matches my hint ... and I think it essentially matches the solutions reported by Norm, Ted, and Marty.

Code:
 r7      Naked  Pair                     <> 58   [r7c56]
     b1  Hidden Triple                   =  269  [r2c3],[r3c23]
 r1  b1  Locked Candidate 1              <> 4    [r1c4]
 r2  b2  Locked Candidate 1              <> 8    [r2c1]

2-Fish c1b5\r34                 fF2 011\200 <> 3  [r3c6]   turbot fish/ER   -or-
2-Fish r6c1\..b4                fm  110\101 <> 3  [r3c6]   grouped 2-String Kite
                    -- or --
2-Fish c16\r3.                  Sk  020\200 <> 3  [r4c4],[r6c23]   Skyscraper

                                              extraneous
2-Fish r2b6\c39                 fF3 101\020 <> 9  [r6c3]   Empty Rectangle

2-Fish r1c1\..b1                fm  110\101 <> 5  [r4c4]   doubly-grouped 2-String Kite

   c4b2  Locked Candidate 2              <> 5    [r2c56],[r3c56]

         XY-Wing  [r4c4]/[r4c7]+[r5c6]   <> 5    [r5c9]

                                              extraneous
2-Fish c5b7\r69                 fF3 011\200 <> 5  [r6c2]   Empty Rectangle

 W-Wing: 6/5 in r2c4,r4c7 connected by 5 in r26c9 => r4c4<>6
 +--------------------------------------------------------------+
 |  8     345   345   |  35    1     9     |  2     6     7     |
 |  57    1     269   | *56    268   2678  |  3     4    %59    |
 |  357   29    269   |  3456  246   2467  |  8     59    1     |
 |--------------------+--------------------+--------------------|
 |  35    7     345   |  4-6   9     1     | *56    2     8     |
 |  6     4589  4589  |  2     7     45    |  1     3     49    |
 |  1     249   245   |  8     456   3     |  569   7    %459   |
 |--------------------+--------------------+--------------------|
 |  2     58    1     |  9     46    46    |  7     58    3     |
 |  4     6     7     |  1     3     58    |  59    589   2     |
 |  9     358   358   |  7     258   258   |  4     1     6     |
 +--------------------------------------------------------------+
 # 68 eliminations remain

Note: The W-Wing from my solver is in a compact notation that I use. So, I substituted a more readable description from HoDoKu in its place.
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tlanglet



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

PostPosted: Thu May 28, 2009 10:32 am    Post subject: Reply with quote

Marty R. wrote:
tlanglet wrote:
I had a four step solution which, after reading the existing posts, are similar.

ER3 with hinge in box2 and strong link in col1 deletes 3 from r4c4,
w-wing 35 deletes 5 in r4c4,
xy-wing 456 with pivot 46 deletes 5 from r5c9,
w-wing 56 deletes 6 from r4c4.

Ted

Mine was identical to Ted's, except I also played an ER on 9 in addition to the one on 3.


Marty, on my first pass I also had an ER on 9, but it was not required to complete the puzzle so I omitted it in my post.

Ted
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