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 denis_berthier » Sat Oct 17, 2020 12:18 am

mith wrote:Since I'm the one adding most of the puzzles at the moment, I don't mind putting up my own version of the database at some point.

In the meantime, could you put your own collection of the SER ≥ 11.7 ?

And I have another question: are you using the same type of proximity search as described e.g. by eleven?
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Re: The hardest sudokus (new thread)

Postby mith » Sat Oct 17, 2020 4:09 am

The ones added in champagne's update are here:

https://drive.google.com/drive/folders/ ... sp=sharing

Each file is ordered by ER/EP/ED, so they're at the top. But here are the 11.7s and 11.8s from those files (I think the only new one since is the 11.8 I just posted).

Code: Select all
........1.....2.3...4.5.6.7...2.8....7..6...59.........16...4...5..1.7..8..3.....;11.7;11.7;2.6
........1....23.....45...6......1....5.7...8.9...5...3.6.8..7...75....4.2.......9;11.7;1.2;1.2
.....9.......8..76...7...85..5.....7.9.....5.1....23...1...4...34..9......681....;11.8;11.8;2.6
..12..3......4..5......6...2.....1.3.4.....6.1.7.....8.1.7......9..65...7..8..2..;11.8;1.5;1.5
........1..2..3.4..4..5.6.......7.8...43......1..9.5...9......63.78.....4....2.7.;11.7;11.7;10.7
........1.....2.3...4.5.6.....2...7..7...4..28...9.5....5..69...1.3.....6.8.4....;11.7;11.7;9.4
........1.....2.34..3.5.6.....6..7...7..8....9....1.4..8.5.....3.1....9.4....3..2;11.7;11.7;8.0
........1.....1..2...34..5...36......574.....8....2....46....7..7.5...6.9...6.1..;11.7;11.7;2.6
.....1..2....3..4....5..1.6..1..72...8......59......8...6..5...43..9....89.3.....;11.7;11.7;2.6
.....1..2....3..4....5..1.6..1..76...8......59......8...5..2...34..9....89.3.....;11.7;11.7;2.6
........1.....2.....3.4.56....7.......4.......5..3.42..26.....8.35..9...4...2.35.;11.7;1.2;1.2
........1....23.4.....452....1.....6.3...6.2.6.7...8....8.5.....5...4...1..6....9;11.7;1.2;1.2
................12..3.145.........4...16......5..371...35....8..749.....1...534..;11.7;1.2;1.2
........1..2..3..4.5..6.27.....8.52.5..9.6...8.......6..76..4...6.....1.2...7.8..;11.7;1.2;1.2


In broad strokes, nothing novel compared to eleven's description. It's still a proximity search, mostly using {-1+2}, {-2+2}, or {-2+1). At the moment I'm only searching 21-24 clues; the 19 and 20 clue searches hadn't yielded anything new in a while. I've got a thread constantly churning through SER ratings, but the generating is filtering on q2 and skfr mostly.
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Re: The hardest sudokus (new thread)

Postby champagne » Sat Oct 17, 2020 7:49 am

mith wrote:The ones added in champagne's update are here: ...


and if you select items with an internal number >3000000 you get yours plus the 2 from sssx
Code: Select all
.....9.......8..76...7...85..5.....7.9.....5.1....23...1...4...34..9......681....   11.8   11.8   2.6   MITH   2020_10   3269469   22   
..12..3......4..5......6...2.....1.3.4.....6.1.7.....8.1.7......9..65...7..8..2..   11.8   1.5   1.5   MITH   2020_10   3268347   22   
........1..2..3.4..4..5.6.......7.8...43......1..9.5...9......63.78.....4....2.7.   11.7   11.7   10.7   MITH   2020_10   3265491   22   
........1.....2.3...4.5.6.....2...7..7...4..28...9.5....5..69...1.3.....6.8.4....   11.7   11.7   9.4   MITH   2020_10   3266306   22   
........1.....2.34..3.5.6.....6..7...7..8....9....1.4..8.5.....3.1....9.4....3..2   11.7   11.7   8   MITH   2020_10   3266003   22   
........1.....2.3...4.5.6.7...2.8....7..6...59.........16...4...5..1.7..8..3.....   11.7   11.7   2.6   MITH   2020_10   3276414   21   
........1.....1..2...34..5...36......574.....8....2....46....7..7.5...6.9...6.1..   11.7   11.7   2.6   MITH   2020_10   3270807   22   
.....1..2....3..4....5..1.6..1..76...8......59......8...5..2...34..9....89.3.....   11.7   11.7   2.6   MITH   2020_10   3269484   22   
12.3.....34..1......5..6...2.....5...1.....2...7..8..9...5..6.7....3..4......79..   11.7   11.7   2.6   SSX   2020_02_29   3261240   22   
.....1..2....3..4....5..1.6..1..72...8......59......8...6..5...43..9....89.3.....   11.7   11.7   2.6   MITH   2020_10   3269482   22   
........1.....2.....3.4.56....7.......4.......5..3.42..26.....8.35..9...4...2.35.   11.7   1.2   1.2   MITH   2020_10   3301956   22   
........1..2..3..4.5..6.27.....8.52.5..9.6...8.......6..76..4...6.....1.2...7.8..   11.7   1.2   1.2   MITH   2020_10   3273143   24   
........1....23.4.....452....1.....6.3...6.2.6.7...8....8.5.....5...4...1..6....9   11.7   1.2   1.2   MITH   2020_10   3302991   22   
................12..3.145.........4...16......5..371...35....8..749.....1...534..   11.7   1.2   1.2   MITH   2020_10   3301994   23   
12.3.....6...7..1...4..5...3.....4...6..2..3...8.....9...9....8.7..3..6......25..   11.7   1.2   1.2   SSX   2019_10   3260101   22   
........1....23.....45...6......1....5.7...8.9...5...3.6.8..7...75....4.2.......9   11.7   1.2   1.2   MITH   2020_10   3267992   21   
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Re: The hardest sudokus (new thread)

Postby denis_berthier » Sat Oct 17, 2020 9:55 am

Mith + Champagne

Thanks for the list
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Re: The hardest sudokus (new thread)

Postby mith » Tue Nov 24, 2020 5:41 pm

I forgot to post my morph of the 11.8 21C I found (keeping with the theme of fitting 11.8 on a diagonal...)

Code: Select all
+-------+-------+-------+
| . . . | . . . | . . 9 |
| . . . | . . . | . 8 . |
| . 7 . | . 6 . | 5 . . |
+-------+-------+-------+
| . . . | 4 . . | . 3 . |
| . 5 . | . 2 . | . . . |
| 1 . . | . . 7 | 6 . . |
+-------+-------+-------+
| 7 1 . | . 5 . | 2 . . |
| 2 . . | . . 1 | . . . |
| . . 9 | 8 . . | . . 3 |
+-------+-------+-------+
........9.......8..7..6.5.....4...3..5..2....1....76..71..5.2..2....1.....98....3  ED=11.8/1.2/1.2


Otherwise, since the database update I also have a new 11.7 (22C), ten eleven 11.6s, and just over 10k new 11+. I'll get a full update up sometime in December maybe.

Code: Select all
........1.......2...3..45......6...7..5..8....9.3..4...39..58...8.9.....2...1..7.  ED=11.8/ 1.2/ 1.2
........1....23......4.5.3...16..7...3...4...8.6.....9..97..8...2..4..5.6........  ED=11.6/11.6/ 9.8
........1.....2..3..4.5..6..1....7..4.6.8....5..9...4..2...3...6.5......8...6..9.  ED=11.6/11.6/ 2.6

........1.....2.3...4.5.6....7.6.8...6.....9238.........857.....5.8..4..1....9...  ED=11.7/11.7/10.5
........1.....2.3.....1.4.5..2..3....4..6.7..6..8...9...89......6..5...771....5..  ED=11.6/11.6/ 7.8
........1.....2.3...4.5.6.......7..2..8....1..9..8.5...467......89..3...5...6.4..  ED=11.6/11.6/ 3.4 (+MFC)

........1.......2...1.345...1..462..3..7.....4...1..8..5......2.6.9.....1...653..  ED=11.6/11.6/ 2.6
........1.....1.23...24.5....26.7....8..5....9...8......7..6.3.4.3....168.....9..  ED=11.6/11.6/ 2.6
........1.....2.....3.4..5.....6.5....54.7....6.3...7...6.7.84.8.......99.4.3..6.  ED=11.6/ 1.2/ 1.2

........1.....2.....3.4..56...4.......4...5.7.6..7.3....685..7.8....96..9.5.6..3.  ED=11.6/ 1.2/ 1.2
..............1..2..3.4.56........27..6..5....8..3.65.....5.48..38.69....54.....6  ED=11.6/ 1.2/ 1.2 (+MFC)
..............1..2..3.4.56........27..6..5....8..3.6......5.48..38.69..5.54.....6  ED=11.6/ 1.2/ 1.2 (+MFC)
........1.....2.3...4.516.....1.......1.754..89.2.......25....6.4...7.5..7...62..  ED=11.6/ 1.2/ 1.2 (+MFC)


*I assume these are all new, I haven't actually gotten around to updating my database to champagne's latest.
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Re: The hardest sudokus (new thread)

Postby mith » Fri Nov 27, 2020 9:48 pm

This one may also be of interest, for the high q1:

Code: Select all
........1....23.....45...6...57...4...62.8.7..9......8..7..2...46.....2.5..6..7..  ED=11.2/1.2/1.2 q1=99431 q2=99489


Also worth noting this pair of 22Cs in the October update:

Code: Select all
........1.....2.3...4.5.6....6....1..4.7....38...9.4....85......6..8..949.5......  ED=11.6/1.2/1.2 q1=99225 q2=99130
........1.....2.3...4.5.6....6....1..4.7....38...9.4....8..9....6..8.5.49.5......  ED=11.6/1.2/1.2 q1=99225 q2=99130


I believe these are the 4th and 5th puzzles to hit ER>=11.6, q1>=99000, AND q2>=99100. (Easter Monster and a couple by eleven are the others.)
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Re: The hardest sudokus (new thread)

Postby mith » Tue Jan 05, 2021 5:09 pm

I was made aware of this: https://www.reddit.com/r/sudoku/comment ... m_scratch/

Recreated (a morph of) an Ocean puzzle (Christmas present for gsf).
Last edited by mith on Wed Jan 06, 2021 11:27 pm, edited 1 time in total.
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Re: The hardest sudokus (new thread)

Postby 999_Springs » Wed Jan 06, 2021 5:16 am

mith wrote:I was made aware of this: https://www.reddit.com/r/sudoku/comment ... nt/ghxsx92
Recreated (a morph of) an Ocean puzzle (Christmas present for gsf).

edit: i read the reddit thread and i see that you are talking about the puzzle in the op and not the comment thread that you linked. in other words, the puzzle is this one
..9...2...8.5...1.7.......6..6.9.....5.8..3..4....7........4..9.3..1..8....2..5..
and not this one, which is the one you gave a direct link to
8..........36......7..9.2...5...7.......457.....1...3...1....68..85...1..9....4..

i take it from your new account on reddit that you are /u/newman-iknewit? as a correction in your reply to the reddit post, the other puzzle they're talking about isn't arto inkala's ai escargot (2006) but a different puzzle that he had published in 2012 long after se 11.9's had been discovered. his new puzzle is se 10.7 but starts with a multi fish and it reduces to 9.0. for the benefit of those reading this thread who may come from reddit, the arto inkala puzzle has been beaten to death several times before here and here and here and by me here and here, which i will let those on reddit know about in a bit when i wake up

edit 2: since the op didn't provide the original puzzle they started from that hodoku rates 27792, and hodoku ratings aren't invariant under isomorphism, there is some chance the op started from the same puzzle and just came up with an isomorph of it by accident, especially if they only did a vicinity search or something
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Re: The hardest sudokus (new thread)

Postby mith » Wed Jan 06, 2021 11:27 pm

Thanks, fixed link.
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Re: The hardest sudokus (new thread)

Postby mith » Mon Mar 08, 2021 10:03 pm

Found my first new 11.7 in a while; I've mostly been running reductions on lower rated puzzles in my database, so not as many high SE ratings.

Code: Select all
........1.....2.34..4.3.5....5.1..4..6.2..7..8..9.......7.2...552...8...9..6..... ED=11.7/11.7/2.8


Has a JE, but still 11.7 after that.
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Re: The hardest sudokus (new thread)

Postby denis_berthier » Wed Mar 10, 2021 6:22 am

mith wrote:Found my first new 11.7 in a while; I've mostly been running reductions on lower rated puzzles in my database, so not as many high SE ratings.
Code: Select all
........1.....2.34..4.3.5....5.1..4..6.2..7..8..9.......7.2...552...8...9..6..... ED=11.7/11.7/2.8

Has a JE, but still 11.7 after that.

It's good to know someone is still looking for more "hardest" puzzles.
Nowadays, a new 11.7 becomes a rarity. I therefore computed it's BpB rating. All the previously known 11.7s fall between B4B and B6B, with the majority of them in B5B (see the tables in chapter 11 of [PBCS]).
This one is in B5B (or less). [As I'm mainly interested in the hardest BpB ratings, I didn't check if it was in a lower BpB.]
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Re: The hardest sudokus (new thread)

Postby creint » Thu Mar 18, 2021 4:42 pm

My solver can now solve all the hardest puzzles.
Forcing nets inside forcing nets is the maximum that is required to solve them.

Code: Select all
98.7.....7.....6....6.5.....4...5.3...79..5......2...1..85..9......1...4.....3.2.

Takes 8 seconds, but this last steps it only take the first found.
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Re: The hardest sudokus (new thread)

Postby Hajime » Thu Mar 18, 2021 8:18 pm

creint wrote:Forcing nets inside forcing nets is the maximum that is required to solve them.
Is your implementation a 2 deep T&E ?
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Re: The hardest sudokus (new thread)

Postby creint » Thu Mar 18, 2021 10:14 pm

place a -> placements+exclusions. Take this as new pencil mark grid and solve, if contradiction then a is invalid.
If you call forcing net 1 deep T&E then yes.
An easy/slower implementation but it can use all the logic.
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Re: The hardest sudokus (new thread)

Postby denis_berthier » Fri Mar 19, 2021 2:55 am

creint wrote:My solver can now solve all the hardest puzzles.
Forcing nets inside forcing nets is the maximum that is required to solve them.

All the known puzzles can be solved with T&E at levels ≤=2.
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