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Puzzle 11/05/03: ~ Difficult (BBDB?)

 
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Tue May 03, 2011 3:49 pm    Post subject: Puzzle 11/05/03: ~ Difficult (BBDB?) Reply with quote

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

Play this puzzle online at the Daily Sudoku site
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tlanglet



Joined: 17 Oct 2007
Posts: 2461
Location: Northern California Foothills

PostPosted: Wed May 04, 2011 2:06 pm    Post subject: Reply with quote

anp(38=4)r56c7-(3)r5c7=r6c7-(3=8)r6c1-r9c1=(8)r9c7; r38c7<>8 which sets up an

Flightless axy-wing (49-3) vertex (49)r3c7 with fin (8)r5c7; r2c5<>3=9
If xy-wing is true: (3)r5c7-r5c4=(3)r4c5;
If fin is true: (8)r5c7-r9c7=r9c1-r6c1=(8-3)r4c3=(3)r4c5;

In preparing this post, I realized these two steps could be combined to make a flightless axy-wing with TWO fins: (8)r3c7 and (8)r5c7. Viewed in this manner, both fins use the identical path to also delete (3) in r2c5. I assume that some kind of ALS could be formed using this pattern making it simpler to state and to understand.

[Edited to add ALS-XZ; r2c5<>3=9]
ALS "A": (39)r2c9
ALS "B": (3489)r356c7
Shared exclusive is (9)
Shared common is (3)
ALS A: If r2c9<>9 then, r2c9=3
ALS B: If r3c7<>9, then ls(348)r356c7-(8)r9c7=r9c1-r6c1=(8-3)r4c3=(3)r4c5;

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Wed May 04, 2011 4:41 pm    Post subject: Reply with quote

My solver found a few UR eliminations present after basics:

Code:
 after basics
 +--------------------------------------------------------------+
 |  7     9     4     |  368   5     2     |  1     368   368   |
 |  6     8     1     |  4     39    7     |  5     2     39    |
 |  5     3     2     |  689   1     689   |  489   468   7     |
 |--------------------+--------------------+--------------------|
 |  1     4     38    |  5    *89+3 *89    |  6     7     2     |
 |  9     2     7     |  38    6     1     |  348   458   458   |
 |  38    5     6     |  7     2     4     |  38    9     1     |
 |--------------------+--------------------+--------------------|
 |  4     1     5     |  2    *89   *89+6  |  7     368   3689  |
 |  238   6     38    |  189   7     5     |  2489  148   489   |
 |  28    7     9     |  16    4     3     |  28    156   56    |
 +--------------------------------------------------------------+
 # 55 eliminations remain

 r89c17  <28> UR Type 4.2234             <> 8    r8c17

 r47c56  <89> UR via s-link              <> 89   r7c6
 r17c89  <36> UR via s-link              <> 6    r7c8

Now, after several hours of tracking down a single typo, it can use simple internal UR conjugates in a chain:

Code:
 (8)r3c6 = r13c4 - (8=3)r5c4 - (3)r4c5 =UR= (6)r7c6  =>  r3c6<>6; r7c6<>8

Unfortunately, it doesn't add anything new to what my solver had already found for this puzzle. _ Sad _


Ted: your solution also works as a nice chain:

Code:
 (3=9)r2c9-(9=348)r356c7-(8)r9c7=r9c1-r6c1=(8-3)r4c3=(3)r4c5  =>  r2c5<>3=9
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tlanglet



Joined: 17 Oct 2007
Posts: 2461
Location: Northern California Foothills

PostPosted: Wed May 04, 2011 7:04 pm    Post subject: Reply with quote

daj95376 wrote:
My solver found a few UR eliminations present after basics:

Code:
 after basics
 +--------------------------------------------------------------+
 |  7     9     4     |  368   5     2     |  1     368   368   |
 |  6     8     1     |  4     39    7     |  5     2     39    |
 |  5     3     2     |  689   1     689   |  489   468   7     |
 |--------------------+--------------------+--------------------|
 |  1     4     38    |  5    *89+3 *89    |  6     7     2     |
 |  9     2     7     |  38    6     1     |  348   458   458   |
 |  38    5     6     |  7     2     4     |  38    9     1     |
 |--------------------+--------------------+--------------------|
 |  4     1     5     |  2    *89   *89+6  |  7     368   3689  |
 |  238   6     38    |  189   7     5     |  2489  148   489   |
 |  28    7     9     |  16    4     3     |  28    156   56    |
 +--------------------------------------------------------------+
 # 55 eliminations remain

 r89c17  <28> UR Type 4.2234             <> 8    r8c17

 r47c56  <89> UR via s-link              <> 89   r7c6
 r17c89  <36> UR via s-link              <6>  r3c6<>6; r7c6<>8

Unfortunately, it doesn't add anything new to what my solver had already found for this puzzle. _ Sad _


Ted: your solution also works as a nice chain:

Code:
 (3=9)r2c9-(9=348)r356c7-(8)r9c7=r9c1-r6c1=(8-3)r4c3=(3)r4c5  =>  r2c5<>3=9

Danny,

I believe that I also found some AURs but they did not offer obvious help, so...............

Thanks for posting the chain. I tend to go with my initial solution regardless of how convoluted it may be. Your chain is clearly the simplest and easiest to understand.

Ted
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Marty R.



Joined: 12 Feb 2006
Posts: 5063
Location: Rochester, NY, USA

PostPosted: Fri May 06, 2011 6:07 am    Post subject: Reply with quote

Code:

+----------+-------------+---------------+
| 7   9 4  | 368 5   2   | 1    368 368  |
| 6   8 1  | 4   39  7   | 5    2   39   |
| 5   3 2  | 689 1   689 | 489  468 7    |
+----------+-------------+---------------+
| 1   4 38 | 5   389 89  | 6    7   2    |
| 9   2 7  | 38  6   1   | 348  458 458  |
| 38  5 6  | 7   2   4   | 38   9   1    |
+----------+-------------+---------------+
| 4   1 5  | 2   89  689 | 7    368 3689 |
| 238 6 38 | 189 7   5   | 2489 148 489  |
| 28  7 9  | 16  4   3   | 28   156 56   |
+----------+-------------+---------------+

Play this puzzle online at the Daily Sudoku site

X-Wing (8) in rows 69 brings us here.

Code:

+---------+-------------+--------------+
| 7  9 4  | 368 5   2   | 1   368 368  |
| 6  8 1  | 4   39  7   | 5   2   39   |
| 5  3 2  | 689 1   689 | 49  468 7    |
+---------+-------------+--------------+
| 1  4 38 | 5   389 89  | 6   7   2    |
| 9  2 7  | 38  6   1   | 34  458 458  |
| 38 5 6  | 7   2   4   | 38  9   1    |
+---------+-------------+--------------+
| 4  1 5  | 2   89  689 | 7   368 3689 |
| 23 6 38 | 189 7   5   | 249 148 489  |
| 28 7 9  | 16  4   3   | 28  156 56   |
+---------+-------------+--------------+

Play this puzzle online at the Daily Sudoku site

XY-Wing (493), flightless, pivoted in r3c7. Transport 3 from r2c9 to r1c4; r5c4<>3.
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