Programs which generate, solve, and analyze Sudoku puzzles
A follow-up on this -- Sudoku Assistant now identifies Sashimi. There were a couple of bugs in the program yesterday, but these have been fixed.

You can check it out at

http://www.stolaf.edu/people/hansonr/sudoku/ex_A1s.htm

and

http://www.stolaf.edu/people/hansonr/sudoku/explain.htm#sashimi
Bob Hanson

Posts: 75
Joined: 04 December 2005

Bob Hanson wrote:For example:

this one

So I think there may be some that are not reducible -- unless you see a smaller set here as well.

{r5c24 r7c1234}

Took me 2 seconds to spot it...
Once upon a time I was a teenager who was active on here 2007-2011
ocean and eleven should have paired up to make a sudoku-solving duo called Ocean's Eleven
999_Springs

Posts: 420
Joined: 27 January 2007
Location: In the toilet, flushing down springs, one by one.

Superb work! Thanks very much for that -- there was a bug -- Sudoku Assistant was not looking for X-Wing-Sashimi. Now that that's fixed, I'm certain that the

n x n Rows == m x m Columns

grid equivalence carries over to a

n x n sashimi Rows == m x m sashimi Columns

equivalence.

I guess that is what you were trying to tell me in the first place.... that there's always a simpler alternative.

Probably a very simple proof of that.

In any case, thanks for the help -- Sudoku Assistant should be finding all Sashimi now, and finding always the smaller alternative.

When I'm done running the test examples, the "A1g" class will be gone -- all those are Sashimi.
Bob Hanson

Posts: 75
Joined: 04 December 2005

You might consider combining almost-locked grids with your newly-discovered "almost-locked ranges":
Code: Select all
`. . .|. . .|/ / 5. 5 .|5 . .|5 5 5. | .|| . .|/ / 5--|--+|----+-----. 5 .|5 . .|. . *. | .|| . .|. . .. | .|| . .|. . .--|--+|----+-----. 5 .|5 . .|. . *. . .|. . .|. . .. . .|. . .|. . .*<>5`

I don't know how useful they might be...

One thing I have noticed in your solver that seems not to have occurred before is the strange choice of subsets. Of course, for every naked subset there is a corresponding hidden one and vice versa, but your solver sometimes finds the larger subset.

Here you can use a naked pair instead of the hidden triple.

And your only example of a hidden quad can be replaced by a naked triple.
Once upon a time I was a teenager who was active on here 2007-2011
ocean and eleven should have paired up to make a sudoku-solving duo called Ocean's Eleven
999_Springs

Posts: 420
Joined: 27 January 2007
Location: In the toilet, flushing down springs, one by one.

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