## Rotational Sudoku

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

### Rotational Sudoku

Rotational Sudoku
-----------------

for the lazy people; each clue multiplies by 4 :

symbols permute by (permutation in cycle-notation)
(1,2,3,4)(5)(6,7,8,9), when the grid is rotated.

Code: Select all
`1236.....5642........1...........................................................rated easy`

whenever cell C contains symbol s then C rotated by 90'
counter-clockwise contains symbol p(s) with
p(1)=2
p(2)=3
p(3)=4
p(4)=1
p(5)=5
p(6)=7
p(7)=8
p(8)=9
p(9)=6

so in the above example the 4 corners must be:
Code: Select all
`1.......4...............................................................2.......3`

etc.

the other sudoku rules apply.

Can someone make a rotational sudoku with 9 different clues
or with 8 clues ?

-Guenter
Last edited by dukuso on Sun Oct 16, 2005 6:03 am, edited 1 time in total.
dukuso

Posts: 479
Joined: 25 June 2005

Not enough places to put the 5's, maybe? One of them must go in the centre, but where would the... Ok, I see how now...

But you're still forced to put the 5 in r5c5, and the puzzle is forced to be diagonal (aka Sudoku X).

The fact that the 5 is forced to be there means you don't have to provide it to the solver. Although you could make the rotation groups unknown. But you still can't only include 7 different numbers if you do this...

LA
Lardarse

Posts: 106
Joined: 01 July 2005

Lardarse wrote:Not enough places to put the 5's, maybe? One of them must go in the centre, but where would the... Ok, I see how now...

But you're still forced to put the 5 in r5c5, and the puzzle is forced to be diagonal (aka Sudoku X).

The fact that the 5 is forced to be there means you don't have to provide it to the solver. Although you could make the rotation groups unknown. But you still can't only include 7 different numbers if you do this...

LA

there is a unique solution.
Yes, a 5 must be in the center.
No, the puzzle is not necessarily diagonal, although there can only
be one 5 in any of the two main diagonals and this 5 is in the center.
The other 8 fives are rotational symmetrically arranged.

Here is one with 9 different clues:

Code: Select all
`1235.....69.......7........8..4..................................................`
dukuso

Posts: 479
Joined: 25 June 2005

Hmm...

Since one number implies a few others, maybe you could get away with only 6 clues...
Lardarse

Posts: 106
Joined: 01 July 2005