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.