The New Sudoku Players' Forum

[MarcusMuscle]

Hello, I've had trouble solving this Rossini sudoku.

The rules for this variant are here : http://www.cross-plus-a.com/html/cros7rsis.htm

The grid :

Code: Select all

      v    v
 *-----------*
 |...|3..|...|
>|..9|...|...|
>|...|...|3..|
 |---+---+---|
<|...|.6.|..2|
<|...|..5|..6|
<|...|...|9.7|
 |---+---+---|
 |...|.1.|...|
 |...|..8|...|
 |.9.|2..|...|
 *-----------*
  ^    v


Little spoiler :

Hidden Text: Show

I've determined that there was 9 above the 2 in the middle-down box, because the 9 in this box can't be in the last row because of the other 9 in this row, and then by Rossini's rules it can only be there.

Aside from that, I did not manage to make any progress with this grid. I've determined a lot of things, ruled out a lot of possibilities, but nothing gave me another digit.

I would love if someone could give me one of the next digit to find, and with what method they managed to find it, so I might learn how to finish it alone ! Any tips and tricks on Rossini's Sudoku are welcome as well

Thank you !

[Hajime]

Are you sure there are no < and > at the right ?

[1to9only]

The OP Rossini sudoku is correctly copied from:

Someone posted a unique solution here: Link.

[MarcusMuscle]

Oh, I didn't know there was a puzzle stack exchange question about this one.

Thank you, that's very useful !

[1to9only]

Rossini sudoku can be converted into GreaterThan sudoku:
Edit1: Image withdrawn. As pointed out by next post, image had arrows pointed the wrong direction!!
Edit2: I've updated the sudoku image. The image in the next post is auto-corrected!!

Edit3: This Rossini sudoku cannot be turned into a GreaterThan sudoku coz of r6c789 - see posts below.

[thelardoffear]

Rossini sudoku can be converted into GreaterThan sudoku:

That picture has the constraints in the wrong direction

e.g. R2C2 must be > 9.

Also converting to a Greater Than sudoku loses the other Rossini rule that triple cells without an arrow do not form a sequence (in either direction) which means that the above puzzle would have hundreds of solutions.

[Hajime]

Also converting to a Greater Than sudoku loses the other Rossini rule that triple cells without an arrow do not form a sequence (in either direction) which means that the above puzzle would have hundreds of solutions.

Which is not the case because in row 6 between the 9 and 7 there can not be an 8.
I could not solve it up to now and have to define extra constraints like non-descending triples like kropki or xv-puzzles.

[Mathimagics]

It appears that according to the rules, the OP's puzzle is invalid (has no solution), because r6c789 = "9.7" has no arrow.

The rules clearly state that a lack of an arrow implies that the corresponding 3 cells do NOT form a sequence.

And so, the equivalence between Rossini and Sudoshiki puzzles is not available. Which is a pity, since it would be much easier to render and solve these without creating new software, and new format strings, etc ...

Cheers
MM

[Hajime]

It appears that according to the rules, the OP's puzzle is invalid (has no solution), because r6c789 = "9.7" has no arrow.

If you put a 6 between the 9 and 7, the sequence is not descending or ascending, which is correct with no arrow.
The link from 1to9only shows the solution of the puzzle.

[Mathimagics]

Urrrggh ..

You are right of course, about the OP puzzle.

[Hajime]

At this moment busy implementing GreaterThan, Kropki and XV variants.
All have symbols on borders what is not possible in the current version of SiSeSuSo.
I am in doubt also to implement Rossini....
Triples with no arrow could be implemented like (< and >) or (> and <) in a GreaterThan .
Indeed extra software and extra format strings. Decisions, decisions...