200e200w's Nightmare #21

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200e200w's Nightmare #21

Postby 200e200w » Sat Feb 17, 2018 11:40 am

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

200e200w
200e200w
 
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Re: 200e200w's Nightmare #21

Postby Cenoman » Sat Feb 17, 2018 10:00 pm

Simple two-step solutions exist. Let's try this one-step:
Code: Select all
 +-------------------------+------------------------+---------------------+
 |  459    245    8        |  3     1259    7       |  6      59   14     |
 |  7      1      6        |  4     589     89      |  2      3    59     |
 |  459    3      2459     |  125   6       129     |  14     8    7      |
 +-------------------------+------------------------+---------------------+
 |  2      457    1457     |  15    1458    3       |  4589   59   6      |
 |  1458   6      3        |  9     1458    148     |  7      2    45     |
 |  458    9      45       |  26    7       26      |  458    1    3      |
 +-------------------------+------------------------+---------------------+
 |  1459   245    12459    |  126   12349   12469   |  1359   7    8      |
 |  3      2457   124579   |  8     1249    1249    |  159    6    1259   |
 |  6      8      129      |  7     1239    5       |  139    4    129    |
 +-------------------------+------------------------+---------------------+

Double kraken:
1a. Kraken row (1)r4c345
(1)r4c3 - r5c1 = r7c1 - (1=26)r67c4 - (2)r3c4
(1-5)r4c4 = (5-2)r3c4
(1)r4c5
This demonstrates (2)r3c4 => (1)r4c5 (could be written !1r4c5 - 2r3c4 as well, where "!" is the symbol of logic NOT)

1b. Kraken cell (125)r3c4 using inference 1a
(1)r3c4
(2)r3c4 => (1)r4c5
(5)r3c4 -r3c13 = r1c12 - r1c8 = r4c8 - (5=4)r5c9 - (4=1)r1c9
=> -1 r1c5; stte

(line #2 of this kraken could be written (2)r3c4 - !(1)r4c5 = (1)r4c5). It is also possible to draw a net...)
Cenoman
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Re: 200e200w's Nightmare #21

Postby pjb » Sat Feb 17, 2018 10:46 pm

Best I can do is 2 simple chains
(5=4)r5c9 - r5c56 = (4-8)r4c5 = (8-9)r4c7 = r4c8 => -5 r4c8
(5s at r78c2 only ones column => -5 r7c13, r8c3)
(1)r1c5 = (1-4)r1c9 = r5c9 - (4=1)r5c6 => -1 r45c5, r3c6
Phil
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