The New Sudoku Players' Forum

[tdillon]

I found this puzzle has nearly perfect balance in the templates survived after direct eliminations from the given pencilmarks.

That sounds like an interesting metric. Have you found that this balance is correlated with difficulty? If so it would be interesting to explore whether this can be used as a heuristic to aid in searching for difficult puzzles.

My solver finds the solution to tdillon's sukaku in 0.45s, but has never completed the proof of uniquness.

Perhaps your solver's heuristics are tuned for minlex presentation of puzzles?

[tarek]

I found this puzzle has nearly perfect balance in the templates survived after direct eliminations from the given pencilmarks.

That sounds like an interesting metric. Have you found that this balance is correlated with difficulty? If so it would be interesting to explore whether this can be used as a heuristic to aid in searching for difficult puzzles.

I think this was the latest observation/metric that dobrichev observed and with it eleven was able to expand the hardest list even further:
http://forum.enjoysudoku.com/the-hardest-sudokus-new-thread-t6539-270.html#p210708

[dobrichev]

No. This is unrelated, entirely different observation.

[mith]

Ran into another puzzle skfr fails to rate; Output 2 is:

...........1..2..3.4..5.16.........7.5.....1.1...8.54...5.1.48.4..9...3.86....... ED=0.0/0.0/0.5

(SE 1.17.7.1 rates this an 11.0.)

[champagne]

Ran into another puzzle skfr fails to rate; Output 2 is:

...........1..2..3.4..5.16.........7.5.....1.1...8.54...5.1.48.4..9...3.86....... ED=0.0/0.0/0.5

(SE 1.17.7.1 rates this an 11.0.)

I ran skfr and got 10.9/1.2/1.2 ???

[mith]

Strange. Maybe my version is old.

[champagne]

This old wersion of SKFR remains relatively slow for me rating millions of puzzles in the high levels to update the database of potential hardest.
SKFR has been written years ago, starting from a frame of code not at all oriented to produce an efficient clone of Sudoku Explainer.

As the meter for the length, Sudoku Explainer rating is somehow a reference of the possible difficulty of a sudoku that everybody understand and that nobody wants to change.

And as for the meter, small adjustments of the definition remain possible to avoid small problems linked to the original definition.

Years later, I think possible to write a new version of SKFR much better for hard puzzles. Expected improvement is big enough to push me to start a new design, the target remaining to be as close as possible to Sudoku Explainer's rating.

This will be in C++ and using intel set of instructions.
Anybody willing to contribute to this new version is welcome.

[champagne]

in line with the lowest activity in the forum, nobody came.

As I need this update of SKFR to continue to work on the n digits end pattern, I try to do this alone.
I reached cloning the area of UR/UL, trying to find a good process in this place where no bypass is possible (unpredictable effect on the final rating).

Hope to reach the end in 2/3 months

[champagne]

starting now cloning of chains,
this is the place where a significant improvement in performance is expected.
Nobody showed interest to see the draft.
bi values chains should be quickly covered

[yzfwsf]

I wonder if the new SKFR will offer support for Sukaku?

[champagne]

I never worked on suklakus, so I am not sure at all to give the right answer,
but with small adjustments, I think that the process is valid for any start PM with a unique solution.

The first step in the process is to apply the brute solver to find the solution and to setup the start PM.
Later, only unsolved cells and the current PM are used to apply serate rules.

If I am right, a sukaku is a PM that you can't get from a list of given, so you can force the start and the solution.

[champagne]

nothing really new, just a kind of milestone to say that the process is still ongoing.

The new version of skfr reached the y chain rating (around 6.7); still to early to say if the target of a new delivery in august is realistic, but ..

I still believe that this new code will be much faster.

[yzfwsf]

I never worked on suklakus, so I am not sure at all to give the right answer,
but with small adjustments, I think that the process is valid for any start PM with a unique solution.

The first step in the process is to apply the brute solver to find the solution and to setup the start PM.
Later, only unsolved cells and the current PM are used to apply serate rules.

If I am right, a sukaku is a PM that you can't get from a list of given, so you can force the start and the solution.

Is the new code an improvement on the original code, or a rewrite?Please go ahead and support the Sukaku rating system. I’m not sure if the launch will happen in August as scheduled, but I hope for good news. Thank you for your outstanding work!

[champagne]

I never worked on suklakus, so I am not sure at all to give the right answer,
but with small adjustments, I think that the process is valid for any start PM with a unique solution.

The first step in the process is to apply the brute solver to find the solution and to setup the start PM.
Later, only unsolved cells and the current PM are used to apply serate rules.

If I am right, a sukaku is a PM that you can't get from a list of given, so you can force the start and the solution.

Is the new code an improvement on the original code, or a rewrite?Please go ahead and support the Sukaku rating system. I’m not sure if the launch will happen in August as scheduled, but I hope for good news. Thank you for your outstanding work!

Hi "yzfwsf",

As I intend to finish with a much faster version of skfr, this will be a complete new code.

Bad effect, I spend plenty of time to optimize each step or the process. Aging and having other constraints, this can finish with more time needed to come to the end.

I am to-day trying to find the best process in the area ER 6.5 / 7.5.

I hoped to have other contributors, this did not come, so we have to work with what a 84 years old guy can do.

[yzfwsf]

Hi champagne ,
Wow, it is truly an honor to look at your work. An 84-year-old developer writing optimized, high-performance code from scratch is legendary!Please take it easy and don't rush. The area you are exploring (ER 6.5 / 7.5) sounds fascinating, and we are happy to wait for as long as it takes. Your health and comfort are the top priorities.
Since you mentioned hoping for other contributors to get involved, is there a public branch or code repository where you could push your current progress (even if it's not yet finished)? Perhaps AI could assist you.
Cheers,YZF