The New Sudoku Players' Forum

[shamath]

Hi,

I am stuck with this and I know there are X-wing and other solutions but I cannot recognize them. Can you help me how to find which are pointing pairs and wings? Most of the sites I read about techniques use easy examples and do not really explain how to find them.

Thanks in advance.

http://forum.enjoysudoku.com/download/file.php?mode=view&id=1370

[999_Springs]

where can you put a 1 in block 3?

what does this tell you about the rest of the 1's in a particular column?

that should take you to the end

[eleven]

There is a hidden pair 13 in box 3.
You can see 13 in row 1 and column 9, leaving only the 2 cells r23c7 (marked x) in box 3 for them. So they must be there, and you can eliminate the other candidates from the2 cells, and all 13's in the rest of column 7.

Code: Select all

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

Yes, in this case it would have been sufficient to see, that 1 is restricted to the 2 cells, and can't be in r8c7.

[shamath]

There is a hidden pair 13 in box 3.
You can see 13 in row 1 and column 9, leaving only the 2 cells r23c7 (marked x) in box 3 for them. So they must be there, and you can eliminate the other candidates from the2 cells, and all 13's in the rest of column 7.

Code: Select all

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

Yes, in this case it would have been sufficient to see, that 1 is restricted to the 2 cells, and can't be in r8c7.

Thanks, I can see now. Appreciate your help.