## Can 17 cell have symmetrical clues within an 8x8 area?

Everything about Sudoku that doesn't fit in one of the other sections

### Can 17 cell have symmetrical clues within an 8x8 area?

The pattern of the clues in this hard Sudoku has 180 rotational symmetry but the grid has a whole is completely asymmetrical:

Code: Select all
`8 6 . . . 1 5 9 . 4 . . . . 7 . 2 . 5 3 2 . . 9 . . . . . . 5 1 . . . . . . . 2 3 . . . . . . 4 . . 6 8 3 . 9 . 1 . . . . 6 . 7 2 6 . . . 1 5 . . . . . . . . . . `

Here are three more puzzles with the same mask, increasingly easier:

13...857.7....4.2.694..2......47.......18......1..983.5.7....9.283...61..........
67...124.4....8.3.892..6......48.......15......1..378.3.4....2.958...61..........
51...728.9....4.3.382..6......23.......61......3..865.7.6....4.895...71..........

[EDITED to delete factual errors]
Might there be found a 17 cell which has all of it's clues in an 8x8 area with diagonal mirror symmetry, similar to the following 23 clue puzzle? (Rotational symmetry is impossible in an 8x8 area with an odd number of clues, as is any of the other mirror symmetries.)

Code: Select all
` . . . 6 5 4 3 8 .  . . 8 . . 7 2 4 .  . 7 . . . . 9 1 .  4 . . . 2 . . 3 .  . . . 8 . . . 5 .  . . 9 . . . 4 . .  . 6 . . . 9 . . .  5 . . . 8 . . . .  . . . . . . . . . `
Last edited by tso on Thu Jun 08, 2006 3:49 pm, edited 1 time in total.
tso

Posts: 798
Joined: 22 June 2005

### Re: Can 17 cell have symmetrical clues within an 8x8 area?

tso wrote:I *believe* no one has found 17 cell Sudoku with symmetry
Here are 10 examples.
Red Ed

Posts: 633
Joined: 06 June 2005

Don't know how I missed that. I've edited the original post.
tso

Posts: 798
Joined: 22 June 2005