The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |...|...|.63|
 |..4|.8.|..5|
 |.27|..5|...|
 |---+---+---|
 |...|.56|.7.|
 |4..|9.3|..1|
 |.8.|14.|...|
 |---+---+---|
 |...|5..|81.|
 |7..|.6.|9..|
 |15.|...|...|
 *-----------*


Play/Print this puzzle online

[Sudtyro2]

Code: Select all

+----------------+----------------+----------------+
| 8    19    5   |  247   179 249 |  1247 6   3    |
|c36*  c1-36 4   | a36+7* 8   29  | b17   29  5    |
|c369  2     7   |  346   139 5   | b14  b49  8    |
+----------------+----------------+----------------+
| 239  39    1   |  8     5   6   |  234  7   249  |
| 4    7     6   |  9     2   3   |  5    8   1    |
| 5    8     239 |  1     4   7   |  236  23  269  |
+----------------+----------------+----------------+
| 2369 3469  239 |  5     379 249 |  8    1   247  |
| 7    34    8   |  234   6   1   |  9    5   24   |
| 1    5     29  |  247   79  8   |  2346 234 2467 |
+----------------+----------------+----------------+

Almost Naked Pair(*)...
NP(36)r2c14 == 7r2c4 - (7=149)b3p478 - (9=361)b1p457 => - 36r2c2; stte

SteveC

[SpAce]

NP(36)r2c14 == 7r2c4 - (7=149)b3p478 - (9=361)b1p457 => - 36r2c2; stte

Hi Steve! Very nice as usual. A minor notation detail, but I don't see the reason for the "==" which usually means a derived strong link. This one could be simply "(36=7)r2c14 - ...", correct? Works just as well both ways, of course, but I might reserve the "==" for cases when the strong link is not as obvious.

[Sudtyro2]

NP(36)r2c14 == 7r2c4 - (7=149)b3p478 - (9=361)b1p457 => - 36r2c2; stte

Hi Steve! Very nice as usual. A minor notation detail, but I don't see the reason for the "==" which usually means a derived strong link. This one could be simply "(36=7)r2c14 - ...", correct? Works just as well both ways, of course, but I might reserve the "==" for cases when the strong link is not as obvious.

Hi SpAce! Thanks for the feedback...
I'm right in the middle of how to best express that first link...
I originally learned about this type of notation as a "Pattern vs. Spoiler." Obi-Wan called the spoiler an "Obstacle." There is a definite strong-inference link between the two. I think Cenoman also discussed the link as being either "derived" or "native." Since it's definitely not "native" IMHO, I now prefer Cenoman's use of the "==" symbol for those derived cases. I think that may also help the less experienced chain developers to better understand the source of the difference in linking notations.

SteveC

[eleven]

This would do it in the same cells:
(1=9)r3c78 - (9=1)b1p457 => -1r2c7, stte

But i found no better way for this move (?):

Code: Select all

 *------------------------------------------------------------------*
 |  8     d19     5     |  247  e179   249   |  1247   6     3      |
 |  36     136    4     |ga367   8     29    |  17     29    5      |
 | c369    2      7     | b346 fb139   5     |  14     49    8      |
 |----------------------+--------------------+----------------------|
 |  239    39     1     |  8     5     6     |  234    7     249    |
 |  4      7      6     |  9     2     3     |  5      8     1      |
 |  5      8      239   |  1     4     7     |  236    23    269    |
 |----------------------+--------------------+----------------------|
 |  2369   3469   239   |  5     379   249   |  8      1     247    |
 |  7      34     8     |  234   6     1     |  9      5     24     |
 |  1      5      29    |  247   79    8     |  2346   234   2467   |
 *------------------------------------------------------------------*

(3|6)r2c4 = hp36r3c45 - (3|6=9)r3c1 - (9=1)r1c2 - r1c5 = (1-36)r3c45 = (3|6)r2c4 => -7r2c4

[SpAce]

I'm right in the middle of how to best express that first link...
I originally learned about this type of notation as a "Pattern vs. Spoiler." Obi-Wan called the spoiler an "Obstacle." There is a definite strong-inference link between the two. I think Cenoman also discussed the link as being either "derived" or "native." Since it's definitely not "native" IMHO, I now prefer Cenoman's use of the "==" symbol for those derived cases. I think that may also help the less experienced chain developers to better understand the source of the difference in linking notations.

Thanks for the explanation, Steve! I'm sure there are multiple ways of seeing this, and in no way did I imply yours was incorrect (or that mine is necessarily correct). However, to me a derived strong link means something a bit more complicated that usually needs either an external or an inline explanation, such as DP+2 situations where the strongly linked candidates can be quite remote (and usually the link is strong-only). I've seen examples of other kinds as well, where a remote strong link has been derived through some clever logic first and then used in chains, but I can't think of any myself right now.

I don't see almost locked sets, finned fishes or in fact any normal almost-patterns (including almost-AICs) belonging to that category, because the OR-relationship between the pattern and the spoiler/obstacle is easy to see anyway and it's direct (either the spoiler is true or the pattern is true). To me the normal "=" marker works just fine in those cases, because they're really no different from the "native" bivalue or bilocation strong links (which are in fact almost-naked-singles or almost-hidden-singles) or group-strong-links (which are almost-locked-candidates). DPs etc are different because they're the reason for the strong link but they don't appear as nodes in the chain themselves (they act as catalysts of sort), hence the strong links are "derived".

[pjb]

Code: Select all

 8       19      5      | 247    179    249    | 1247   6      3     
c36     c136     4      | 367    8      29     | 7-1    29     5     
c369     2       7      | 346    139    5      |a14    b49     8     
------------------------+----------------------+---------------------
 239     39      1      | 8      5      6      | 234    7      249   
 4       7       6      | 9      2      3      | 5      8      1     
 5       8       239    | 1      4      7      | 236    23     269   
------------------------+----------------------+---------------------
 2369    3469    239    | 5      379    249    | 8      1      247   
 7       34      8      | 234    6      1      | 9      5      24     
 1       5       29     | 247    79     8      | 2346   234    2467 

(1=4)r3c7 - (4=9)r3c8 - (9=361)r2c12, r3c1 => -1 r2c7; stte

Phil