Sudoku Players' Forum (clone)

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If you have a pair (two cells in the same house both of which can only contain the same two digits) you can't have those two digits anywhere else in that same house. A house is a row, column, or box.

In you first example, the pair on 47 eliminates 4 & 7 from all of the other cells in that column, but doesn't tell you anything about the 37, which is not in the same column.

RyanStorm,

note that both the 47 box in the 1st and the left 47 box in the 3rd row could be 4 in your first picture. So the 7 in the 37 box is still possible.

But your picture shows a "remote pair" pattern.
If the box with 4 or 7 in the first row is 4, then the one in row 7 must be 7, and vice versa, if the one is 7, the other is 4.
That means, that (taking the row/column numbering of the second picture) the box in row 7 and column 9 cannot be 4 or 7, because 4 and 7 are in these 2 boxes, in the same column or row resp.

However we cannot see, if this would help you in this puzzle.

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My solver treats a Remote Pair as two XY-Chains using the same cells. (see below)

Code: Select all

 +-----------------------------------------------------------------------+
 |  234    24     5      |  9      37     8      |  1      6     a47     |
 |  34     7      9      |  34     6      1      |  5      2      8      |
 |  1      8      6      |  2      5     c47     |  3     b47     9      |
 |-----------------------+-----------------------+-----------------------|
 |  9      126    7      |  5      24     3      |  8      14     246    |
 |  268    1256   3      |  78     2478   69     |  2679   14579  24567  |
 |  268    256    4      |  1      278    69     |  2679   579    3      |
 |-----------------------+-----------------------+-----------------------|
 |  7      46     2      |  34     39     5      |  69     8      1      |
 |  45     9      8      |  6      1     d47     |  27     3      25-7   |
 |  56     3      1      |  78     789    2      |  4      579    567    |
 +-----------------------------------------------------------------------+
 # 65 eliminations remain

 RP (7=4)r1c9 - (4=7)r3c8 - (7=4)r3c6 - (4=7)r8c6  =>  r8c9<>7
 RP (4=7)r1c9 - (7=4)r3c8 - (4=7)r3c6 - (7=4)r8c6  =>  nada


However, you are now stuck on where to go after the Remote Pair. There are two choices that I would recommend.

(1) Look for other XY-Chains present. Especially those that contain a <4> in the starting cell.

(2) Learn about "Fish" patterns. There are several for <4> and <6> that crack your puzzle.


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