The New Sudoku Players' Forum

[Mickeyb]

When I dubbed The Wisconsin State Journal's Sudoku puzzle of today (11/12/2005), it registered as invalid. Has anyone solved the puzzle?

6X3 XX1 X8X
X84 3XX 2XX
52X XXX XXX

X7X XXX XX4
XXX 657 XXX
2XX XXX X1X

XXX XXX X45
XX8 XX3 17X
X5X 4XX 8X3

I'm sorry if this is the wrong forum. Please email me if this is/is not a valid puzzle. Thanks. mickeyb@tds.net

[PaulIQ164]

It's a valid puzzle in the sense that there is only one correct solution, but Pappocom considers it "invalid" because it requires some very tricky techniques to solve, that ar either very hard to find with pencil and paper, or else might be considered by some to be Trial and Error.

[nj3h]

The same puzzle was in the Northern Virginia Daily, 12 Nov 05. The copyright says Knight Features, Distributed by Universal Press Syndicate. I will call the newspaper Monday and tell them that they are putting out puzzles that require T&E to solve. Sadman requires T&E to solve it. I don't use Simple Sudoku, can someone please check and see if that program can solve it with other than T&E?

Thanks,
George

[Pappocom]

I will call the newspaper Monday and tell them that they are putting out puzzles that require T&E to solve.

... and let them know they can have Pappocom puzzles for free!

- Wayne

[angusj]

... and let them know they can have Pappocom puzzles for free! - Wayne

I have, a couple of times, when they've approached me (though not this crowd) .

[rubylips]

The first thirteen moves, which are all straightforward, lead to the following position:

Code: Select all

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


whereupon the going gets tougher for two moves:

Code: Select all

14. The value 1 in Box 4 must lie in Row 5.
- The moves r4c1:=1 and r4c3:=1 have been eliminated.
Consider the chain r7c2~6~r6c2-6-r4c3-6-r4c7-6-r7c7.
When the cell r7c2 contains the value 6, so does the cell r7c7 - a contradiction.
Therefore, the cell r7c2 cannot contain the value 6.
- The move r7c2:=6 has been eliminated.
Consider the chain r7c1~7~r2c1-7-r2c5~7~r3c4-7-r7c4.
When the cell r7c1 contains the value 7, so does the cell r7c4 - a contradiction.
Therefore, the cell r7c1 cannot contain the value 7.
- The move r7c1:=7 has been eliminated.
Consider the chain r4c5-3-r6c5-3-r6c2-6-r4c3-6-r4c7.
When the cell r4c7 contains the value 3, some other value must occupy the cell r4c5, which means that the value 6 must occupy the cell r4c7 - a contradiction.
Therefore, the cell r4c7 cannot contain the value 3.
- The move r4c7:=3 has been eliminated.
The cell r5c7 is the only candidate for the value 3 in Column 7.
15. The values 1, 2, 3 and 8 occupy the cells r4c1, r4c4, r4c5 and r4c6 in some order.
- The moves r4c1:=9, r4c4:=9, r4c5:=9 and r4c6:=9 have been eliminated.
The value 9 in Row 6 must lie in Box 5.
- The move r6c9:=9 has been eliminated.
Consider the chain r5c1-8-r4c1-3-r6c2-6-r8c2-4-r8c1.
When the cell r5c1 contains the value 4, so does the cell r8c1 - a contradiction.
Therefore, the cell r5c1 cannot contain the value 4.
- The move r5c1:=4 has been eliminated.
The cell r5c2 is the only candidate for the value 4 in Row 5.


It's easy again after that.

[Hud]

The same puzzle was in the AZ Republic on the same day. I tried it with paper and also got stuck and I also couldn't dub it even after placing additional obvious big numbers in cells. They showed a rating of 6 bright stars for it. I don't feel ready for advanced techniqyes yet.