January 23, 2018

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January 23, 2018

Postby ArkieTech » Tue Jan 23, 2018 12:11 pm

Code: Select all
 *-----------*
 |94.|.58|.2.|
 |...|6..|...|
 |..1|..4|9.5|
 |---+---+---|
 |...|..7|..1|
 |.6.|.9.|.7.|
 |3..|1..|...|
 |---+---+---|
 |2.7|5..|4..|
 |...|..2|...|
 |.5.|84.|.92|
 *-----------*


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Re: January 23, 2018

Postby 200e200w » Tue Jan 23, 2018 3:03 pm

Code: Select all
.---------------------.---------------------.---------------------.
| 9      4      6     | 37     5      8     | 1      2      7-3   |
| 57     23     25    | 6      1      9     | a38    g348   h47-3 |
| 78     38     1     | 237    23     4     | 9      6      5     |
:---------------------+---------------------+---------------------:
| 458    28     9     | 234    2368   7     | 2568-3 3458   1     |
| 1      6      c2458 | 234    9      35    | b258-3 7      i34   |
| 3      7      e2458 | 1      268    56    | 2568   f458   9     |
:---------------------+---------------------+---------------------:
| 2      9      7     | 5      36     36    | 4      1      8     |
| 48     1      d48   | 9      7      2     | 35     35     6     |
| 6      5      3     | 8      4      1     | 7      9      2     |
'---------------------'---------------------'---------------------'

(3=8)r2c7 - r5c7 = r5c3 - (8=4)r8c3 - r6c3 = r6c8 - r2c8 = r2c9 - (4=3)r5c9 => -3 r12c9,r45c7; stte

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Re: January 23, 2018

Postby Cenoman » Tue Jan 23, 2018 5:19 pm

Code: Select all
 +--------------------+--------------------+-----------------------+
 |  9     4    6      |  37    5      8    |  1       2      37    |
 |  57    23   25     |  6     1      9    | b38     a38-4  i347   |
 |  78    38   1      |  237   23     4    |  9       6      5     |
 +--------------------+--------------------+-----------------------+
 |  458   28   9      |  234   2368   7    |  23568   3458   1     |
 |  1     6   d2458   |  234   9      35   | c2358    7     h34    |
 |  3     7   f2458   |  1     268    56   |  2568   g458    9     |
 +--------------------+--------------------+-----------------------+
 |  2     9    7      |  5     36     36   |  4       1      8     |
 |  48    1   e48     |  9     7      2    |  35      35     6     |
 |  6     5    3      |  8     4      1    |  7       9      2     |
 +--------------------+--------------------+-----------------------+

(8)r2c8 = r2c7 - r5c7 = r5c3 - (8=4)r8c3 - r6c3 = r6c8 - r5c9 = (4)r2c9 => -4 r2c8; stte
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Re: January 23, 2018

Postby SteveG48 » Tue Jan 23, 2018 7:34 pm

Code: Select all
 *--------------------------------------------------------------------*
 | 9      4      6      | 37     5      8      | 1      2      37     |
 |c57    b23    b25     | 6      1      9      |a38    a348    347    |
 | 78     38     1      | 237    23     4      | 9      6      5      |
 *----------------------+----------------------+----------------------|
 |d458  cd28     9      | 234    2368   7      | 23568 e3458   1      |
 | 1      6      2458   | 234    9      35     | 2358   7     e34     |
 | 3      7      2458   | 1      268    56     | 2568   58-4   9      |
 *----------------------+----------------------+----------------------|
 | 2      9      7      | 5      36     36     | 4      1      8      |
 | 48     1      48     | 9      7      2      | 35     35     6      |
 | 6      5      3      | 8      4      1      | 7      9      2      |
 *--------------------------------------------------------------------*


(4=3)r2c78 - (3=25)r2c23 - (5|2)r2c1,r4c2 = (58)r4c12 - (5|8=4)b6p26 => -4 r6c8 ; stte
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Re: January 23, 2018

Postby Leren » Tue Jan 23, 2018 7:52 pm

Code: Select all
*----------------------------------------------*
| 9   4  6    | 37  5    8  | 1      2    7-3  |
| 57  23 25   | 6   1    9  |a38     348  47-3 |
| 78  38 1    | 237 23   4  | 9      6    5    |
|-------------+-------------+------------------|
| 458 28 9    | 234 2368 7  | 2568-3 3458 1    |
| 1   6 c2458 | 234 9    35 |b258-3  7   d34   |
| 3   7 e2458 | 1   268  56 | 2568  f458  9    |
|-------------+-------------+------------------|
| 2   9  7    | 5   36   36 | 4      1    8    |
| 48  1 d48   | 9   7    2  | 35     35   6    |
| 6   5  3    | 8   4    1  | 7      9    2    |
*----------------------------------------------*

A bit shorter than the first solution :

(3=8) r2c7 - r5c7 = r5c3 - (8=4) r8c3 - r6c3 = r6c8 - (4=3) r5c9 => - 3 r12c9, r45c7; stte

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Re: January 23, 2018

Postby Sudtyro2 » Tue Jan 23, 2018 8:43 pm

Code: Select all
+-----------------+---------------+------------------+
|  9    4   6     | 37  5    8    |  1     2    37   |
| c57  c23 c25    | 6   1    9    | c38   c348  347  |
| d78   38  1     | 237 23   4    |  9     6    5    |
+-----------------+---------------+------------------+
|  58-4 28  9     | 234 2368 7    |  23568 3458 1    |
|  1    6   2458  | 234 9    35   |  2358  7    34   |
|  3    7  a2458  | 1   268  56   |  2568 b458  9    |
+-----------------+---------------+------------------+
|  2    9   7     | 5   36   36   |  4     1    8    |
| d48   1   8-4   | 9   7    2    |  35    35   6    |
|  6    5   3     | 8   4    1    |  7     9    2    |
+-----------------+---------------+------------------+

4r6c3 = r6c8 - (4=23587)r2c12367 - (7=84)r38c1 => -4r8c3,r4c1; stte.

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Re: January 23, 2018

Postby 200e200w » Tue Jan 23, 2018 10:07 pm

Hi Leren,
(3=8) r2c7 - r5c7 = r5c3 - (8=4) r8c3 - r6c3 = r6c8 - (4=3) r5c9 => - 3 r12c9, r45c7; stte

I didn't see the weak link (4)r6c8 - r5c9. That's why my chain is so long and not as elegant as yours. I'll try to improve it in later puzzles.

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Re: January 23, 2018

Postby 200e200w » Tue Jan 23, 2018 10:27 pm

Hi Steve,
(4=3)r2c78 - (3=25)r2c23 - (5|2)r2c1,r4c2 = (58)r4c12 - (5|8=4)b6p26 => -4 r6c8 ; stte

Your chain (or in reality Net) should be written as:
Code: Select all
(4=38)r2c78 - (3=25)r2c23 - (5)r2c1 = r4c1 - r4c8
                         \                      \\
                          (2=8)r4c2 - r4c8 ===== (34)b6p26 => -4 r6c8; stte


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Re: January 23, 2018

Postby Marty R. » Tue Jan 23, 2018 10:59 pm

Code: Select all
┌───────────────────────┬───────────────────────┬───────────────────────┐
│     9       4       6 │    37       5       8 │     1       2      37 │
│                       │                       │                       │
│    57      23      25 │     6       1       9 │    38     348     347 │
│                       │                       │                       │
│    78      38       1 │   237      23       4 │     9       6       5 │
├───────────────────────┼───────────────────────┼───────────────────────┤
│   458      28       9 │   234    2368       7 │ 23568    3458       1 │
│                       │                       │                       │
│     1       6    2458 │   234       9      35 │  2358       7      34 │
│                       │                       │                       │
│     3       7    2458 │     1     268      56 │  2568     458       9 │
├───────────────────────┼───────────────────────┼───────────────────────┤
│     2       9       7 │     5      36      36 │     4       1       8 │
│                       │                       │                       │
│    48       1      48 │     9       7       2 │    35      35       6 │
│                       │                       │                       │
│     6       5       3 │     8       4       1 │     7       9       2 │
└───────────────────────┴───────────────────────┴───────────────────────┘


Kite (4) hinged b6
4r2c9=r6c3
4r2c9-(4=3)r5c9
4r6c3-(4=358)r268c8-(358=4)r2684c8-(4=3)r5c9=> 3r5c9
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Re: January 23, 2018

Postby 200e200w » Tue Jan 23, 2018 11:12 pm

Hi Marty R.,
Kite (4) hinged b6
4r2c9=r6c3
4r2c9-(4=3)r5c9
4r6c3-(4=358)r268c8-(358=4)r2684c8-(4=3)r5c9=> 3r5c9

According to how the candidates for 4 are placed in c8, your chain is incorrect, because (4)r6c3 - (4=358)r268c8 is incorrect. You cannot prove that r5c9=3 using these chains. The correct chain could be:
Code: Select all
(4)r6c3 - r6c8 =====================================\
       \                                            \\
        (4=8)r8c3 - r5c3 = r5c7 - r2c7 = (8-4)r2c8 = r4c8 - (4=3)r5c9


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Re: January 23, 2018

Postby Marty R. » Wed Jan 24, 2018 12:23 am

200e200w wrote:Hi Marty R.,
Kite (4) hinged b6
4r2c9=r6c3
4r2c9-(4=3)r5c9
4r6c3-(4=358)r268c8-(358=4)r2684c8-(4=3)r5c9=> 3r5c9

According to how the candidates for 4 are placed in c8, your chain is incorrect, because (4)r6c3 - (4=358)r268c8 is incorrect. You cannot prove that r5c9=3 using these chains. The correct chain could be:
Code: Select all
(4)r6c3 - r6c8 (=====================================\)
      (\)                                           (\\)
        (4=8)r8c3 - r5c3 = r5c7 - r2c7 = (8-4)r2c8 = r4c8 - (4=3)r5c9


200e200w


OK, I agree. I was doing the puzzle off an incorrect grid, in which r2c8 was 38 rather than 348. I don't understand the portion of your notation that I've enclosed in ().
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Re: January 23, 2018

Postby pjb » Wed Jan 24, 2018 6:42 am

Code: Select all
 9       4       6      | 37     5      8      | 1      2      37     
 57      23      25     | 6      1      9      |ag38    g348    347   
 78      38      1      | 237    23     4      | 9      6      5     
------------------------+----------------------+---------------------
 458     28      9      | 234    2368   7      | 23568  3458   1     
 1       6      c2458   | 234    9      35     |b2358   7      34     
 3       7      e2458   | 1      268    56     | 2568  f458    9     
------------------------+----------------------+---------------------
 2       9       7      | 5      36     36     | 4      1      8     
 48      1      d48     | 9      7      2      | 35     35     6     
 6       5       3      | 8      4      1      | 7      9      2     

(3=8)r2c7 - r5c7 = r5c3 - (8=4)r8c3 - r6c3 = r6c8 - (38)r2c78 => -3r12c9, r2c2; stte

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Re: January 23, 2018

Postby 200e200w » Wed Jan 24, 2018 7:27 am

Hi Phil,
(3=8)r2c7 - r5c7 = r5c3 - (8=4)r8c3 - r6c3 = r6c8 - (38)r2c78 => -3r12c9, r2c2; stte

Should be:
(3=8)r2c7 - r5c7 = r5c3 - (8=4)r8c3 - r6c3 = r6c8 - (4=38)r2c78 => -3r12c9, r2c2; stte

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Re: January 23, 2018

Postby SteveG48 » Wed Jan 24, 2018 2:43 pm

200e200w wrote:Hi Steve,
(4=3)r2c78 - (3=25)r2c23 - (5|2)r2c1,r4c2 = (58)r4c12 - (5|8=4)b6p26 => -4 r6c8 ; stte

Your chain (or in reality Net) should be written as:
Code: Select all
(4=38)r2c78 - (3=25)r2c23 - (5)r2c1 = r4c1 - r4c8
                         \                      \\
                          (2=8)r4c2 - r4c8 ===== (34)b6p26 => -4 r6c8; stte


200e200w


Hi, 200e200w. Thanks for reading and for the comment.

I certainly agree that my chain can be written as you've indicated, but I don't agree that it should be, and I don't see why you would want to.

As I've written it, the chain is a bi-directional AIC and follows that rules posted by David P. Bird:

"Nevertheless for an alternating inference chain to be bi-directional the same basic rules must always be followed.
1) Each term in the chain must be a Boolean which will be interpreted as either being true or false
2) The link types must alternate between weak and strong
3) Each link must be stand-alone and independent of the truth states of candidates elsewhere in the chain."

To me, rule 3 is the thing that distinguishes between a net solution and a non-net solution. As a matter of personal preference, I always try to present a solution as a bi-directional AIC if I can, provided that the notation doesn't get ridiculously complex. I admit to not always being successful on either count.
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Re: January 23, 2018

Postby 200e200w » Wed Jan 24, 2018 3:47 pm

Hi Steve,
As I've written it, the chain is a bi-directional AIC...

For me, it isn't a bi-directional AIC. I also think that it doesn't follow the rule 3:
3) Each link must be stand-alone and independent of the truth states of candidates elsewhere in the chain."

That's my opinion.

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