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An extra hard BB?

 
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keith



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

PostPosted: Thu Mar 12, 2009 12:24 am    Post subject: An extra hard BB? Reply with quote

The Brain Basher's Super Hard from a week ago seems to be much harder than normal. Am I missing something?
Code:
Puzzle: BB030209sh
+-------+-------+-------+
| . 7 . | . 3 . | . 4 . |
| 6 . . | . 2 . | . . 5 |
| . . 4 | 8 . 1 | 9 . . |
+-------+-------+-------+
| . . 7 | . . . | 1 . . |
| 2 8 . | . . . | . 7 9 |
| . . 6 | . . . | 4 . . |
+-------+-------+-------+
| . . 9 | 2 . 3 | 5 . . |
| 7 . . | . 1 . | . . 3 |
| . 3 . | . 6 . | . 2 . |
+-------+-------+-------+

(Normally, they take an X- or XY-wing or two.)

There is an incredible UR elimination lurking here!

Keith
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Thu Mar 12, 2009 1:56 am    Post subject: Re: An extra hard BB? Reply with quote

[Withdrawn: What I mentioned would have been obvious to you.]

Last edited by daj95376 on Thu Mar 12, 2009 2:08 am; edited 1 time in total
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Thu Mar 12, 2009 2:06 am    Post subject: Reply with quote

Code:
.---------------------.---------------------.---------------------.
| 1589   7      158   | 569    3      569   | 2      4      18    |
| 6      19     138   | 479    2      479   | 378    138    5     |
| 35     2      4     | 8      57     1     | 9      36     67    |
:---------------------+---------------------+---------------------:
| 3459   459    7     | 356    589    2568  | 1      3568   268   |
| 2      8      135   | 13456  45     456   | 36     7      9     |
| 1359   159    6     | 1357   5789   2578  | 4      358    28    |
:---------------------+---------------------+---------------------:
| 148    146    9     | 2      478    3     | 5      168    14678 |
| 7      456    2     | 45     1      458   | 68     9      3     |
| 1458   3      158   | 4579   6      45789 | 78     2      1478  |
'---------------------'---------------------'---------------------'

for a VH+ type puzzle, that is impressive. just about every move depends on the one before it.
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keith



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

PostPosted: Thu Mar 12, 2009 2:32 am    Post subject: Reply with quote

OK, I put this one through Sudoku Susser.

I believe it belongs on my list of the best Sudoku puzzles ever. I have seven advanced moves, including the incredible UR.

Keith
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Marty R.



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

PostPosted: Thu Mar 12, 2009 3:23 am    Post subject: Reply with quote

I had eight moves, unless you count two ERs as one. Agree it's an excellent puzzle for those who enjoy using a bunch of steps. My UR was a very non-incredible Type 4. I did see a potential DP in the middle stack but there were too many possibilities for me to pursue it.
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keith



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

PostPosted: Thu Mar 12, 2009 9:23 pm    Post subject: Reply with quote

After basics:
Code:

+-------------------+-------------------+-------------------+
| 1589  7     158   | 569   3     569   | 2     4     18    |
| 6     19    138   | 479   2     479   | 378   138   5     |
| 35    2     4     | 8     57    1     | 9     36    67    |
+-------------------+-------------------+-------------------+
| 3459  459   7     | 356   589   2568  | 1     3568  268   |
| 2     8     135   | 13456 45    456   | 36    7     9     |
| 1359  159   6     | 1357  5789  2578  | 4     358   28    |
+-------------------+-------------------+-------------------+
| 148   146   9     | 2     478   3     | 5     168   14678 |
| 7     456   2     | 45    1     458   | 68    9     3     |
| 1458  3     158   | 4579  6     45789 | 78    2     1478  |
+-------------------+-------------------+-------------------+

After an X-wing on <3>, and one on <7>:
Code:

+----------------+----------------+----------------+
| 589  7    58   | 569  3    569  | 2    4    1    |
| 6    19   13   | 479  2    479  | 37   8    5    |
| 35   2    4    | 8    57   1    | 9    36   67   |
+----------------+----------------+----------------+
| 3459 459  7    |356  -589  2568a| 1    356  28d  |
| 2    8    135  | 1456 45   456  | 36   7    9    |
| 1359 159  6    |1357 -589  2578b| 4    35   28c  |
+----------------+----------------+----------------+
| 48   46   9    | 2    478  3    | 5    1    67   |
| 7    456  2    | 45   1    458  | 68   9    3    |
| 158  3    158  | 579  6    5789 | 78   2    4    |
+----------------+----------------+----------------+
abcd is a type-3 UR. and ab make a pseudo-cell <567>. With the following cells in B5, <1456> <45> <1357> <456>, it forms a sextet in <134567>. You can eliminate <5> in the two cells shown.

Keith
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Marty R.



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

PostPosted: Thu Mar 12, 2009 9:28 pm    Post subject: Reply with quote

I don't know that I would've ever seen that. That's the one I played as a Type 4 (SL on 2).
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keith



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

PostPosted: Thu Mar 12, 2009 11:09 pm    Post subject: Reply with quote

Marty R. wrote:
I don't know that I would've ever seen that. That's the one I played as a Type 4 (SL on 2).


Marty,

Right. Another way to look at it: The type-4 takes <8> off of ab. Leaving the hidden pair <89> in B5C5.

Keith
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