July 11, 2017

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July 11, 2017

Postby ArkieTech » Mon Jul 10, 2017 10:55 pm

Code: Select all
 *-----------*
 |7..|6..|3.1|
 |.5.|.1.|..7|
 |...|79.|.4.|
 |---+---+---|
 |4..|...|.15|
 |.6.|.2.|.3.|
 |53.|...|..9|
 |---+---+---|
 |.9.|.31|...|
 |2..|.6.|.7.|
 |3.4|..5|..6|
 *-----------*


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Re: July 11, 2017

Postby SteveG48 » Tue Jul 11, 2017 12:38 am

Code: Select all
 *-----------------------------------------------------------*
 | 7     4    a89    | 6     5     28    | 3    b29    1     |
 | 89    5     3     | 48    1     248   | 269   269   7     |
 | 1     2     6     | 7     9     3     | 5     4     8     |
 *-------------------+-------------------+-------------------|
 | 4     7     9-2   | 3     8     69    |d26    1     5     |
 | 89    6     1     | 5     2     79    | 78    3     4     |
 | 5     3   ad28    | 1     4     67    | 2678 c268   9     |
 *-------------------+-------------------+-------------------|
 | 6     9     7     | 48    3     1     | 48    5     2     |
 | 2     18    5     | 9     6     48    | 148   7     3     |
 | 3     18    4     | 2     7     5     | 189   89    6     |
 *-----------------------------------------------------------*


(2=89)r16c3 - (9=2)r1c8 - (2=6|8)r6c8 - (6&8=2)r4c7,r6c3 => -2 r4c3 ; stte
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Re: July 11, 2017

Postby Leren » Tue Jul 11, 2017 12:41 am

Code: Select all
*--------------------------------------------------------------*
| 7     4     8-9    | 6     5     28     | 3    a29    1      |
| 89    5     3      | 48    1     248    | 269   269   7      |
| 1     2     6      | 7     9     3      | 5     4     8      |
|--------------------+--------------------+--------------------|
| 4     7     29aA   | 3     8     69     | 26a   1     5      |
| 89    6     1      | 5     2     79     | 78    3     4      |
| 5     3     28A    | 1     4     67     | 2678 b268bB 9      |
|--------------------+--------------------+--------------------|
| 6     9     7      | 48    3     1      | 48    5     2      |
| 2     18    5      | 9     6     48     | 148   7     3      |
| 3     18    4      | 2     7     5      | 189   89    6      |
*--------------------------------------------------------------*

3 Petal Death Blossom: Stem Cell r6c8 {268} :

(9=2) r1c8  - (2) r6c8;

(9=6) r4c37 - (6) r6c8;

(9=8) r46c3 - (8) r6c8; => - 9 r1c3, stte

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Re: July 11, 2017

Postby SteveG48 » Tue Jul 11, 2017 1:02 am

Nice one, Leren. I'm kicking myself for not seeing that, since r6c8 is also the key cell in my own solution. Normally I like bi-directional AICs best, but Death Blossoms are always a favorite.
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Re: July 11, 2017

Postby pjb » Tue Jul 11, 2017 2:03 am

Code: Select all
 7       4     *d89     | 6      5      28     | 3     *29     1     
 89      5       3      | 48     1      248    | 269    269    7     
 1       2       6      | 7      9      3      | 5      4      8     
------------------------+----------------------+---------------------
 4       7      c29     | 3      8      69     |b26     1      5     
 89      6       1      | 5      2      79     | 78     3      4     
 5       3       2-8    | 1      4      67     | 2678 *a268    9     
------------------------+----------------------+---------------------
 6       9       7      | 48     3      1      | 48     5      2     
 2       18      5      | 9      6      48     | 148    7      3     
 3       18      4      | 2      7      5      | 189    89     6     

Almost xy-wing at r1c38, r6c8, with (6)r6c8 - (6=2)r4c7 - (2=9)r4c3 - (9=8)r1c3, => -8 r6c3; stte

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Re: July 11, 2017

Postby Cenoman » Tue Jul 11, 2017 9:47 am

After all these nice solutions, very few opportunities to be creative... Try BUG+7 (7 cells, 8 killers) !
Code: Select all
 +-----------------+------------------+--------------------+
 |  7    4    89   |  6    5    28    |  3      29    1    |
 |  89   5    3    |  48   1    24+8  |  69+2   26+9  7    |
 |  1    2    6    |  7    9    3     |  5      4     8    |
 +-----------------+------------------+--------------------+
 |  4    7    29   |  3    8    69    |  26     1     5    |
 |  89   6    1    |  5    2    79    |  78     3     4    |
 |  5    3    28   |  1    4    67    |  2+68-7 68+2  9    |
 +-----------------+------------------+--------------------+
 |  6    9    7    |  48   3    1     |  48     5     2    |
 |  2    18   5    |  9    6    48    |  14+8   7     3    |
 |  3    18   4    |  2    7    5     |  19+8   89    6    |
 +-----------------+------------------+--------------------+

(8)r2c6 - r2c1 = r5c1 - (8=7)r5c7
(2)r2c7 - (2=9)r2c146 - (9=7)r5c17
(9-6)r2c8 = r6c8 - (6=7)r6c6
(6)r6c7
(8)r6c7
(2)r6c8-(2=8)r1c38-r2c1=r5c1-(8=7)r5c7
(8)r8c7-(8=7)r5c7
(8)r9c7-(8=7)r5c7
=> -7 r6c7; stte

Yes, it works !
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Re: July 11, 2017

Postby Leren » Tue Jul 11, 2017 10:07 am

Congratulations on the BUG + 7. I believe it may be a record, beating Marty R by 1.

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Re: July 11, 2017

Postby JC Van Hay » Tue Jul 11, 2017 12:04 pm

Cenoman wrote:After all these nice solutions, very few opportunities to be creative... Try BUG+7 (7 cells, 8 killers) !
In order to be complete :
Code: Select all
+--------------+-------------+---------------+
| 7   4   89   | 6   5  28   | 3     29    1 |
| 89  5   3    | 48  1  24   | 69    26    7 |
| 1   2   6    | 7   9  3    | 5     4     8 |
+--------------+-------------+---------------+
| 4   7   9-2  | 3   8  9-6  | (26)  1     5 |
| 89  6   1    | 5   2  79   | 78    3     4 |
| 5   3   (28) | 1   4  (67) | (72)  (86)  9 |
+--------------+-------------+---------------+
| 6   9   7    | 48  3  1    | 48    5     2 |
| 2   18  5    | 9   6  48   | 14    7     3 |
| 3   18  4    | 2   7  5    | 19    98    6 |
+--------------+-------------+---------------+
Because of the XYWing(268)r6c38.r4c7-(2=9)r4c3 and the XYWing(267)r6c67.r4c7-(6=9)r4c6, the BUG has no solution. Therefore, BUG+7 -> 1 unique solution.
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Re: July 11, 2017

Postby Ngisa » Tue Jul 11, 2017 4:03 pm

Code: Select all
+------------------+---------------------+----------------------+
| 7     4     fC89 |    6     5    gD28  |    3       9-2     1 |
|e89    5       3  |    48    1      248 |    269     269     7 |
| 1     2       6  |    7     9      3   |    5       4       8 |
+------------------+---------------------+----------------------+
| 4     7       29 |    3     8      69  |    26      1       5 |
|d89    6       1  |    5     2     c79  |    78      3       4 |
| 5     3      B28 |    1     4     b67  |    2678  Aa268     9 |
+------------------+---------------------+----------------------+
| 6     9       7  |    48    3      1   |    48      5       2 |
| 2     18      5  |    9     6      48  |    148     7       3 |
| 3     18      4  |    2     7      5   |    189     89      6 |
+------------------+---------------------+----------------------+

Kraken Cell: {268}r6c8
2 r6c8 - (2)r1c8
6 r6c8 - (6=7)r6c6 - (7=9)r5c6 - (9=8)r5c1 - r2c1 = r1c3 - (8=2)r1c6 - (2)r1c8
8 r6c8 - r6c3 = r1c3 - (8=2)r1c6 - (2)r1c8 => - 2 r1c8; stte

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Re: July 11, 2017

Postby Cenoman » Tue Jul 11, 2017 4:11 pm

JC Van Hay wrote:Because of the XYWing(268)r6c38.r4c7-(2=9)r4c3 and the XYWing(267)r6c67.r4c7-(6=9)r4c6, the BUG has no solution. Therefore, BUG+7 -> 1 unique solution.


Thanks JC for your additional work. It leads me to formulate a question that I found no answer to, for long.
I have read that a BUG pattern has either no solution, either 2 solutions. But when you create a BUG with removing from the grid a candidate that you conclude "in fine" to be part of the solution, you know you have removed the actual solution in a cell. If the puzzle had initially a unique solution, it has no solution any longer. This is the basis of T&E or brute force. So, for a valid puzzle having a unique solution, any BUG would have no solution.
I have never seen a BUG with 2 solutions (I do not address so-called BUG-lite) Does any such BUG exist ?

Anyhow, I know your preference for concise solutions. But "BUG+7 -> 1 unique solution" is a bit of an understatement. I find it useful to show readers an elimination that initiates the stte finish...

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Re: July 11, 2017

Postby JC Van Hay » Tue Jul 11, 2017 8:21 pm

Cenoman wrote:I have never seen a BUG with 2 solutions (I do not address so-called BUG-lite) Does any such BUG exist ?
What about this example.
But "BUG+7 -> 1 unique solution" is a bit of an understatement
I meant BUG -> 0 solution and your 8 chains -> -7r6c7; stte of 1 unique solution.

Note : as a general personal rule, each time I am using an "uniqueness technique", I always investigate the number of solutions of the puzzle related to the deadly pattern [so, no "controversy" :roll: in my case].
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Re: July 11, 2017

Postby eleven » Wed Jul 12, 2017 9:32 pm

Cenoman wrote:So, for a valid puzzle having a unique solution, any BUG would have no solution.

Agreed. If it would have 2 solutions, the puzzle could not be unique.
The samples JC pointed at are no BUG's, but deadly uniqueness patterns without any additional candidate.
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