The New Sudoku Players' Forum

[Chris R]

The solution to this puzzle appears to me not to be unique.

In the lower left 1 and 7 can be interchanged.
This propagates to the lower middle ( 1 and 7 interchanged) and then to the middle (1 and 7 interchanged).

[edited to add puzzle number]

[Crazy Girl]

Had the puzzle not given R6C9=7 and R7C9=1, then the puzzle would have two solutions, (known as a pseudo puzzles) as the 1 and 7 in rows 6 and 7 could be interchanged. Since there is a clue in one of these positions it forces the other cells to take a unique solution.

Original Clues

Code: Select all

 7 . . | . . 1 | 4 . 9
 . . 1 | 4 . . | . . .
 9 . . | 3 8 . | . 1 .
-------+-------+------
 1 . . | . . . | 9 5 .
 . . 6 | . . . | 2 . .
 . 3 8 | . . . | . . 7
-------+-------+------
 . 4 . | . 2 8 | . . 1
 . . . | . . 4 | 6 . .
 6 . 2 | 7 . . | . . 5

with solution:

Code: Select all

 7 5 3 | 2 6 1 | 4  8 9
 2 8 1 | 4 5 9 | 3  7 6
 9 6 4 | 3 8 7 | 5  1 2
-------+-------+-------
 1 2 7 | 8 3 6 | 9  5 4
 4 9 6 | 1 7 5 | 2  3 8
 5 3 8 | 9 4 2 | 1* 6 7*
-------+-------+-------
 3 4 5 | 6 2 8 | 7* 9 1*
 8 7 9 | 5 1 4 | 6  2 3
 6 1 2 | 7 9 3 | 8  4 5

hope this is of help

[Chris R]

Thanks!

I had copied out the puzzle on a separate sheet. I assumed, of course, that I had done so correctly! I had not filled in r9c4 with the clue 7.