The New Sudoku Players' Forum

[afortress]

Hi,

Can you please help.
I want to know which techniques the computer used to go from IMG1 to IMG2.
I've attached the screen shots.

Thanks in advance,

[daj95376]

Hi,

Can you please help.
I want to know which techniques the computer used to go from IMG1 to IMG2.
I've attached the screen shots.

Thanks in advance.

Code: Select all

 IMG1 ... plus r4c5 containing <6>
 +--------------------------------------------------------------------------------+
 |  467     8       1       |  467     2       9       | a46      3       5       |
 |  4567    2       4567    |  467     4567    3       |  19      8      b19      |
 |  3456    9       3456    |  468     1       568     | a246     7       246     |
 |--------------------------+--------------------------+--------------------------|
 |  1368    13      9       |  2       367     678     | a346     5       467-3   |
 |  36      7       2       |  5       9       4       |  8       1       6-3     |
 |  3568    4       3568    |  3678    367     1       | a236     9       267-3   |
 |--------------------------+--------------------------+--------------------------|
 |  12347   13      347     |  1347    8       257     |  159-3   6      b139     |
 |  123478  6       3478    |  9       3457    257     |  15-3    24     b138     |
 |  9       5       348     |  1346    346     26      |  7       24     b138     |
 +--------------------------------------------------------------------------------+
 # 109 eliminations remain

   c7    Naked  Quad (a)                 <> 2346 r78c7
   c9    Naked  Quad (b)                 <> 1389 r456c9

         Naked  Single                   =  6    r5c9


It's impossible to tell which of the Naked Quads is performed by the solver, maybe both. If only one Naked Quad was performed, then a Locked Candidate was also performed. Finally, a Naked Single completes the results for IMG2.

What's more important is how r4c5<>6 occurred because it's not justified from what I see.

Regards, Danny