The hardest sudokus (new thread)

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

Re: The hardest sudokus (new thread)

Postby champagne » Wed Oct 23, 2019 12:35 pm

ssxsssxs wrote:Is this 11.7 not a new puzzle? What is the isomorphism puzzle in

It is a new one, now added to my data base
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Re: The hardest sudokus (new thread)

Postby m_b_metcalf » Fri Jan 10, 2020 9:21 am

champagne wrote:This data base is shared to give samples of "potential hardest puzzles".

Until now you've understandably restricted your data base to standard sudokus. However, now that tarek has provided us with a way to rate X-sudokus too, do you think it worth adding a section for that variant? In particular, I believe that these three are rated higher than any others to date (see here):

Code: Select all
..1...2.....3....45........6.3....1..5......6..7..........82.....6.9.....8...7.9.   ED=12.0/12.0/7.7 : Xtreme_bronze
..1...2....23....45........4.6....1..5......7..8..........96.....5.3.....9...8.3.   ED=12.0/12.0/7.8 : Xtreme_silver
..1...2....23....44........5.3....6..1......5..6..........78.......9.....7...1.9.   ED=12.0/12.0/8.1 : Xtreme_gold

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Re: The hardest sudokus (new thread)

Postby champagne » Fri Jan 10, 2020 10:19 am

Hi Mike,

for sure this makes sense.

till now, I did not follow tarek's efforts to extend the scope of "Sudoku Explainer" and I never worked on sudoku variants.
IMO, this should be a separate data base, one for each variant, and the volunteer to do the job should be personally involved in the variant (and if possible relatively young).

Years ago, tarek produced one of the first data bases of hard puzzles, but each of us has some tools to do it.
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Re: Hardest Variants

Postby tarek » Fri Jan 10, 2020 8:05 pm

Hi Mike & Champagne:

There could be a sperate thread for Hardest Variants based on Explainer or others. I think That Latin Square, SudokuX, Windoku and SudokuP are relatively reasonable. Certainly Latin Square is quicker to search & rate with SE and the Mathematics/Computer Sciences community may have an interest in the hardest Latin Square (QWH)

With Sukaku Explainer I can see at least 2 issues:
1. It is constantly being updated & therefore a rating of "x" today may change in the next release
2. There are several options that control the rating: one is the -B option which controls how close SE is to a depth 1st search The other is the -P option which
controls what SE uses as nested techniques in Dynamic forcing chains + and above. Both of these are by default similar to what Sudoku Explainer 1.2.1 does.

The rating therefore is correct for the version of the release being used under the set of parameters utilized. The -S option would output all the parameters used to assist in referencing all of this.

There are few freely available solvers to compare to out there and although I have checked for errors/glitches/bugs, There are very few that would be able to verify that 11 is actually harder than 10. I'm assuming that - without evidence to the contrary - that Sukaku explainer is doing a good job!
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