The New Sudoku Players' Forum

[eleven]

This 'technique' is just a mistake by RW, the first one, i remember, which has not been fixed quickly.
It is not true, that without the extra candidates you always would run into a BUG.
This is a counter example with the grid after singles. Only 0 or 2 candidates of 349 in unsolved cells except in r3c9.
But r3c9=2, not 3.

Code: Select all

.....25....15......6.1.7.8..32..4...1.....7.......89.4....7....6.52.....94.....7.
+-------------------+-------------------+-------------------+
|*34    8     7     |*49    6     2     | 5    *149  *139   |
|*34    2     1     | 5     8    *39    |*346  *469   7     |
| 5     6     9     | 1    *34    7     |*234   8    #2+3   |
+-------------------+-------------------+-------------------+
| 8     3     2     | 7     9     4     | 16    156   156   |
| 1     9     4     | 6     2     5     | 7     3     8     |
| 7     5     6     | 3     1     8     | 9     2     4     |
+-------------------+-------------------+-------------------+
| 2     1     8     |*49    7    *369   |*346  *4569 *3569  |
| 6     7     5     | 2    *34   *139   | 8    *149  *139   |
| 9     4     3     | 8     5     16    | 126   7     126   |
+-------------------+-------------------+-------------------+

[Added for clarity:] The problem is the same as with "normal" BUGs: Not every grid with 2 candidates per cell is a BUG, additionally each candidate has to be exactly twice in each unit.

[MAGREMENT]

It's quite sad that this technique is flawed, I liked it. I don't wanna give it up but I'm scared that adding the 2 candidates by unit condition is just gonna transform this into a BUG-Lite limited to n candidates.

[MAGREMENT]

After some testing, adding the condition makes this technique useless. RIP