The New Sudoku Players' Forum

[newatthis]

this puzzle is suppose to be able to be solved with logic but I can't figure it out...I've solved it by guessing but would like to know if there is a valid solution

_ 5 _ 1 2 9 8 3 _
_ 9 1 3 _ 6 7 2 5
2 _ 3 _ 5 7 9 1 _
5 2 _ _ 9 1 6 8 3
1 3 _ _ _ 2 5 7 9
9 _ 8 _ 3 5 1 4 2
_ _ 2 9 6 3 4 5 1
3 4 9 5 1 8 2 6 7
6 1 5 2 7 4 3 9 8

[Sped]

The puzzle is invalid. You have 2 6s in column 6.

[ronk]

this puzzle is suppose to be able to be solved with logic but I can't figure it out...

Code: Select all

 47  5   67  | 1    2   9   | 8   3   46
 48  9   1   | 3    48  6   | 7   2   5
 2   68  3   | 48   5   7   | 9   1   46
-------------+--------------+------------
 5   2   47  | 47   9   1   | 6   8   3
 1   3   46  | 68+4 48  2   | 5   7   9
 9   67  8   | 67   3   5   | 1   4   2
-------------+--------------+------------
 78  78  2   | 9    6   3   | 4   5   1
 3   4   9   | 5    1   8   | 2   6   7
 6   1   5   | 2    7   4   | 3   9   8

If the puzzle is to have a unique solution, r5c4 must be a 4.

[Myth Jellies]

To explain ronk's answer a little more--the grid of candidates is a BUG+1 grid. The only way to avoid the BUG (which would have multiple solutions if it was true, thus it must not be true) is to set r5c4 = 4. Click on the link above to learn more about the BUG.

[QBasicMac]

The puzzle is invalid. You have 2 6s in column 6.

You must be looking at some other puzzle. This puzzle is just fine.

Mac

[MCC]

Mac, newatthis has amended his grid to accommodate Sped's post re the 6's.


MCC

[QBasicMac]

Mac, newatthis has amended his grid to accommodate Sped's post re the 6's.
MCC

Oh, thanks! I wondered what was happening

MAC

[FEARDIZ]

I used a swordfish with row 1,3, 6 with filter on 6's

[Ruud]

I used a swordfish with row 1,3, 6 with filter on 6's

Rows 1,3, 6 have candidates in 4 columns. A swordfish must consist of 3 rows with candidates in exactly 3 columns.

Ruud.