September 23, 2016

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September 23, 2016

Postby ArkieTech » Thu Sep 22, 2016 11:32 pm

Code: Select all
 *-----------*
 |8..|.1.|.2.|
 |5..|..6|.9.|
 |4..|3..|...|
 |---+---+---|
 |.7.|4..|13.|
 |...|.6.|...|
 |.13|..5|.8.|
 |---+---+---|
 |...|..2|..1|
 |.2.|7..|..9|
 |.5.|.9.|..7|
 *-----------*


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dan
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Re: September 23, 2016

Postby Leren » Thu Sep 22, 2016 11:51 pm

Code: Select all
*-----------------------------------------------------------------------*
| 8      6      7       | 59A    1      49      |a45     2      3       |
| 5      3      1       | 28     248    6       | 7      9      48      |
| 4      9      2       | 3      58A    7       |a56     1     b568bB   |
|-----------------------+-----------------------+-----------------------|
| 269    7      5       | 4      28a    89a     | 1      3      26a     |
| 29     48     48      | 1      6      3       | 59     7      25      |
| 269    1      3       | 2-9    7      5       |a469    8      246     |
|-----------------------+-----------------------+-----------------------|
| 7      48     9       | 568    3458   2       | 38     456    1       |
| 1      2      468     | 7      3458   48      | 38     456    9       |
| 3      5      468     | 68     9      1       | 2      46     7       |
*-----------------------------------------------------------------------*

3 Petal Death Blossom: Stem Cell r3c9 {568} :

(9=5) r136c7     - (5) r3c9;

(9=6) r4c569     - (6) r3c9;

(9=8) r1c4, r3c5 - (8) r3c9; => - 9 r6c4; stte

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Re: September 23, 2016

Postby SteveG48 » Fri Sep 23, 2016 12:53 am

Code: Select all
 *-----------------------------------------------------------*
 | 8     6     7     |a59    1     4-9   |a45    2     3     |
 | 5     3     1     | 28    248   6     | 7     9     48    |
 | 4     9     2     | 3     58    7     | 56    1     568   |
 *-------------------+-------------------+-------------------|
 | 269   7     5     | 4   bc28  bc89    | 1     3    b26    |
 | 29    48    48    | 1     6     3     | 59    7     25    |
 | 269   1     3     |c29    7     5     |S469   8     246   |
 *-------------------+-------------------+-------------------|
 | 7     48    9     | 568   3458  2     | 38    456   1     |
 | 1     2     468   | 7     3458  48    | 38    456   9     |
 | 3     5     468   | 68    9     1     | 2     46    7     |
 *-----------------------------------------------------------*


3 petal death blossom => -9 r1c6 ; stte

Stem: [469]r6c7

Petal a, [459]r1c47; 4r6c7 - (4=59)r1c47 - 9r1c6
Petal b, [2689]r4c569; 6r6c7 - (6=289)r4c569 - 9r1c6
Petal c, [289]b5p237; 9r6c7 - (9=289)b5p237 - 9r1c6

Now the question. The last chain, 9r6c7 - (9=289)b5p237 - 9r1c6, is clearly not a proper AIC since the middle term
has a 9 on both sides of the equal sign. Properly, it should be written 9r6c7 - r6c4 = r4c6 - r1c6, but then it wouldn't
be a death blossom. Petal c is already a locked set. Eliminating the 9 at r6c4 determines which candidates are
where. So is it a proper death blossom?
Steve
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Re: September 23, 2016

Postby Leren » Fri Sep 23, 2016 2:45 am

SteveG48 wrote : So is it a proper death blossom?

I think that whether or not a move has a name is just a matter of style over substance (has the elimination been proved ?).

Death Blossoms are a subset of Kraken cells, where all of the forcing chains are ALS's.

Perhaps you could call your move an "Almost Death Blossom" and be elevated to the Sudoku Hall of Fame for discovering this "new" move :D .

BTW I don't nominate 2 petal Death Blossoms any more, because they are always ALS XY wings with the middle ALS a bi-value cell, and I've never come across a 4 petal Death blossom. Can anyone provide an example ?

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Re: September 23, 2016

Postby SteveG48 » Fri Sep 23, 2016 3:11 am

Leren wrote:
SteveG48 wrote : So is it a proper death blossom?

I think that whether or not a move has a name is just a matter of style over substance (has the elimination been proved ?).


True, and in this case the elimination is obvious. Beyond style, however, I'm interested in the technical issue here. A proper AIC needs for each term to be true, and one term in my third chain isn't true. On the other hand, the logic is fine. So how do you handle this situation technically? I've seen a number of situations in which a set that is already locked is "improved" by a further elimination that pins down the location of the candidates in the set. How should this be handled using Eureka?
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Re: September 23, 2016

Postby Leren » Fri Sep 23, 2016 3:28 am

Well one way is to simply recognize that your 3 cell locked set is also an XY chain.

So you could write your third leg as 9 r6c7 - (9=2) r6c4 - (2=8) r4c5 - (8=9) r4c6 - 9 r1c6.

So all of the intermediate terms are ALSs and it's standard Eureka - just a thought.

Leren

PS You could simplify a bit and write your third leg as 9 r6c7 - (9=2) r6c4 - (2=9) r4c56 - 9 r1c6.

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Re: September 23, 2016

Postby JC Van Hay » Fri Sep 23, 2016 6:13 am

Code: Select all
+--------------+------------------+------------------+
| 8    6   7   | (59)  1     49   | (45)   2    3    |
| 5    3   1   | 28    248   6    | 7      9    48   |
| 4    9   2   | 3     58    7    | 56     1    568  |
+--------------+------------------+------------------+
| 269  7   5   | 4     (28)  (89) | 1      3    (26) |
| 29   48  48  | 1     6     3    | 59     7    25   |
| 269  1   3   | 2-9   7     5    | (469)  8    246  |
+--------------+------------------+------------------+
| 7    48  9   | 568   3458  2    | 38     456  1    |
| 1    2   468 | 7     3458  48   | 38     456  9    |
| 3    5   468 | 68    9     1    | 2      46   7    |
+--------------+------------------+------------------+
[XYWing(459)r1c47.r6c7=6r6c7-(6=289)r4c569]-9r6c4; stte
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Re: September 23, 2016

Postby pjb » Fri Sep 23, 2016 7:14 am

Code: Select all
 8       6       7      | 59     1      49     | 45     2      3     
 5       3       1      | 28     248    6      | 7      9      48     
 4       9       2      | 3      58     7      | 56     1      568   
------------------------+----------------------+---------------------
 269     7       5      | 4      28     89     | 1      3      26     
 29      48      48     | 1      6      3      | 59     7      25     
 269     1       3      | 29     7      5      | 469    8      246   
------------------------+----------------------+---------------------
 7       48      9      | 568    3458   2      | 38     456    1     
 1       2       468    | 7      3458   48     | 38     456    9     
 3       5       468    | 68     9      1      | 2      46     7     

(2-6)r6c1 = (6-9)r4c1
(2-9)r6c4 = r4c6 - r4c1
(2-4)r6c9 = r2c9 - r1c7 = (4-9)r1c6 = r4c6 - r4c1 => -9 r4c1; stte

Phil
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Re: September 23, 2016

Postby Sudtyro2 » Fri Sep 23, 2016 8:38 pm

Code: Select all
 *-----------------------------------------------------------*
 | 8     6     7     | 59    1     49d   | 5-4   2     3     |
 | 5     3     1     | 28    248   6     | 7     9     48    |
 | 4     9     2     | 3     58    7     | 56    1     568   |
 |-------------------+-------------------+-------------------|
 | 269b  7     5     | 4     28c   89c   | 1     3    *26    |
 |*29    48    48    | 1     6     3     | 59    7    *25a   |
 | 269   1     3     | 29    7     5     | 469   8     246   |
 |-------------------+-------------------+-------------------|
 | 7     48    9     | 568   3458  2     | 38    456   1     |
 | 1     2     468   | 7     3458  48    | 38    456   9     |
 | 3     5     468   | 68    9     1     | 2     46    7     |
 *-----------------------------------------------------------*
The CoALS Rule applied to overlapping ALS(*) states that (52=69).
One can then form the short chain segment, (52=69) - (6|9=2)r4c1, which establishes a derived strong link between 5r5c9 and 2r4c1.
It seems OK to then use that link to process a Kraken 2c9 as follows:
Code: Select all
2r5c9 - [5r5c9=2r4c1] - (2=89)r4c56 - (9=4)r1c6 - 4r1c7; stte
 ||                   /                         /
2r4c9 ---------------                          /
 ||                                           /
(2-4)r6c9 = 4r2c9 ---------------------------
The only question might be that 2r5c9 is also one of the three 2s in the overlapping ALS. Is this type of linking allowed?

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Re: September 23, 2016

Postby bat999 » Sat Sep 24, 2016 12:08 am

Code: Select all
.--------------.------------------.-----------------.
| 8    6   7   | a59    1      49 | b45   2     3   |
| 5    3   1   |  28    248    6  |  7    9     48  |
| 4    9   2   |  3     58     7  |  56   1     568 |
:--------------+------------------+-----------------:
| 269  7   5   |  4    a28    a89 |  1    3    b26  |
| 29   48  48  |  1     6      3  |  59   7     25  |
| 269  1   3   |  2-9   7      5  | c469  8     246 |
:--------------+------------------+-----------------:
| 7    48  9   |  568   3458   2  |  38   456   1   |
| 1    2   468 |  7     3458   48 |  38   456   9   |
| 3    5   468 |  68    9      1  |  2    46    7   |
'--------------'------------------'-----------------'
(9=25)r1c4,r4c56 - (2|5=46)r1c7,r4c9 - (4|6=9)r6c7 => -9 r6c4;stte
8-)
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Re: September 23, 2016

Postby Sudtyro2 » Sat Sep 24, 2016 10:42 am

bat999 wrote: (9=25)r1c4,r4c56 - (2|5=46)r1c7,r4c9 - (4|6=9)r6c7 => -9 r6c4;stte

Bat, I like your chain and can follow the logic. It looks like you're sort of propagating "split nodes," but how do you find such an animal?

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Re: September 23, 2016

Postby bat999 » Sat Sep 24, 2016 11:19 am

Sudtyro2 wrote:... propagating "split nodes," but how do you find such an animal?

Hi
I had originally considered 'kraken' cell r6c7...
(4)r6c7 - (4=9)r1c47 - (9)r6c4 [where r1c4 is 9]
(6)r6c7 - (6=9)r4c569 - (9)r6c4 [where r4c6 is 9]
(9)r6c4 - (9)r6c4
=> -9 r6c4
:)

Then I worked backwards to investigate what happens if neither of r1c4 or r4c6 is 9.
The result seems to be a 'split node', but I didn't set out to propagate one deliberately.
;)
8-)
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Re: September 23, 2016

Postby SteveG48 » Sun Sep 25, 2016 1:27 pm

Sudtyro2 wrote:
Code: Select all
 *-----------------------------------------------------------*
 | 8     6     7     | 59    1     49d   | 5-4   2     3     |
 | 5     3     1     | 28    248   6     | 7     9     48    |
 | 4     9     2     | 3     58    7     | 56    1     568   |
 |-------------------+-------------------+-------------------|
 | 269b  7     5     | 4     28c   89c   | 1     3    *26    |
 |*29    48    48    | 1     6     3     | 59    7    *25a   |
 | 269   1     3     | 29    7     5     | 469   8     246   |
 |-------------------+-------------------+-------------------|
 | 7     48    9     | 568   3458  2     | 38    456   1     |
 | 1     2     468   | 7     3458  48    | 38    456   9     |
 | 3     5     468   | 68    9     1     | 2     46    7     |
 *-----------------------------------------------------------*
The CoALS Rule applied to overlapping ALS(*) states that (52=69).
One can then form the short chain segment, (52=69) - (6|9=2)r4c1, which establishes a derived strong link between 5r5c9 and 2r4c1.
It seems OK to then use that link to process a Kraken 2c9 as follows:
Code: Select all
2r5c9 - [5r5c9=2r4c1] - (2=89)r4c56 - (9=4)r1c6 - 4r1c7; stte
 ||                   /                         /
2r4c9 ---------------                          /
 ||                                           /
(2-4)r6c9 = 4r2c9 ---------------------------
The only question might be that 2r5c9 is also one of the three 2s in the overlapping ALS. Is this type of linking allowed?

SteveC


Steve, I don't see any problem with your solution. I'm not sure that I understand the question.
Steve
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Re: September 23, 2016

Postby Sudtyro2 » Sun Sep 25, 2016 7:19 pm

SteveG48 wrote: Steve, I don't see any problem with your solution. I'm not sure that I understand the question.

Thx, Steve, for the feedback. My concern in the first chain above was the initial linking into the CoALS structure via 2r5c9 - (52=69), where 2r5c9 is actually one of three 2s (bold) in the overlapping ALS. The 52 premise says that the single 5-digit and the three 2-digits are logically AND'd. That's what made me a little nervous about the initial weak link. However, it sounds like it's a non-issue.

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Re: September 23, 2016

Postby SteveG48 » Sun Sep 25, 2016 7:38 pm

Sudtyro2 wrote:
SteveG48 wrote: Steve, I don't see any problem with your solution. I'm not sure that I understand the question.

Thx, Steve, for the feedback. My concern in the first chain above was the initial linking into the CoALS structure via 2r5c9 - (52=69), where 2r5c9 is actually one of three 2s (bold) in the overlapping ALS. The 52 premise says that the single 5-digit and the three 2-digits are logically AND'd. That's what made me a little nervous about the initial weak link. However, it sounds like it's a non-issue.

SteveC


I see. Actually, I wouldn't worry about the overlapping ALS and simply treat it as a split node:

2r5c9 - (2=69)r4c9,r5c1 - (6|9=2)r4c1 .......
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