The New Sudoku Players' Forum

[StrmCkr]

This one was posted on redit this morning apprently it might not be in the list of 17s any one care to check

000035080209000000000000000700200000080000030000006000600900200050080000000000407

[JPF]

Not new

JPF

[StrmCkr]

Thanks for checking

[WosRet]

Hello.
Can someone please confirm this 17 clue sudokus as new ones?
Thanks in advance.

Code: Select all

...4...89.56......7..2............7..3.1...........56.....78.......6.....1......3 # 49159
...4...89.56.....27...............7..3.1...........56.....78.......6.....1......3 # 49160
..3.5.7............8.1..........4..1...8.2..49.5............5...1...8.........93. # 49161
...4....9..6.8...27......5........7..3.1...........86.....75....1......3....6.... # 49162


[eleven]

There are no new 17 clue sudokus at all, see here. Don't waste your time.
[Added] in the 17 clue list i have they are equivalent to

Code: Select all

23847:..............1..2..3.4..5.......64..1.7......7.8.2......2....1..4......5.6......
34844:........1.......2...3..4........35...6.......12......7....7.......21..6...4...8.9
35709:........1.......2...3..4..5.....36...5.......21....7......7.......12......4...89.
35716:........1.......2...3..4..5.....36...7.......12...........5.......21.7....4...8.9


[WosRet]

Ok. Thank you for the check.

[denis_berthier]

.
What's the latest update to the collection of 18-clue puzzles (preferably in minlex and still better in solution-minlex form)?
.

[coloin]

Unfortunately the main collator of the project was Mathemagics who sadly is no longer with us. here

One of his last posts on the LCT-18 project was here ....
The end of the low/Hi clue thresholds thread was his last comment on the subject

The current 18C grid count is 635,256,482.

The estimated number of grids with an 18 is ~ 960 million. Collating those puzzles and grid solutions was a pretty good achievement.

Over the years contributors have searched for 18 clue puzzles of varous distributions.
In an 18C puzzle there has to be at least 6 clues in one of the 6 bands and in one of the 6 diagonal boxes !
There is a range of 18C puzzles with 6 clues in all bands. Of these there can be 2 clues in every box which was investigated very nicely here
There is a range of 18C puzzles with maximum number of clues in one ot the 6 diagonals [ 6-13] here

And these 18C puzzles from their respective template were not easy to find by our homework team !

Code: Select all

+---+---+---+        +---+---+---+             
|...|...|...|        |...|...|...|             
|.xx|xxx|xx.|        |...|1..|2..|             
|.xx|xxx|xx.|        |.3.|..4|.5.|             
+---+---+---+        +---+---+---+             
|.xx|...|xx.|        |..2|...|6..|             
|.xx|...|xx.|        |.4.|...|.7.|             
|.xx|...|xx.|        |..8|...|1..|             
+---+---+---+        +---+---+---+             
|.xx|xxx|xx.|        |..1|2..|8..|             
|.xx|xxx|xx.|        |.5.|.37|.4.|             
|...|...|...|        |...|...|...|             
+---+---+---+        +---+---+---+    18C   JPF                                                 
                                               
+---+---+---+        +---+---+---+             
|...|...|...|        |...|...|...|             
|...|...|..x|        |...|...|..9|             
|.xx|xxx|xx.|        |..6|.34|7..|             
+---+---+---+        +---+---+---+             
|.xx|xxx|xx.|        |..7|.9.|...|             
|.xx|xxx|xx.|        |.65|..7|1..|             
|.xx|xxx|xx.|        |...|.2.|.3.|             
+---+---+---+        +---+---+---+             
|.xx|xxx|xx.|        |...|5.1|68.|             
|x..|...|...|        |2..|...|...|             
|...|...|...|        |...|...|...|             
+---+---+---+        +---+---+---+   18C   blue                                           
                                               
+---+---+---+        +---+---+---+             
|...|...|.xx|        |...|...|..1|             
|...|...|.xx|        |...|...|.23|             
|...|..x|...|        |...|..4|...|             
+---+---+---+        +---+---+---+             
|xxx|xxx|x..|        |5..|..6|4..|             
|xxx|xxx|...|        |2..|...|...|             
|xxx|xxx|...|        |37.|.89|...|             
+---+---+---+        +---+---+---+             
|xxx|xxx|...|        |...|.2.|...|             
|xxx|xxx|...|        |..1|37.|...|             
|xxx|xxx|...|        |.48|...|...|             
+---+---+---+        +---+---+---+   18C   JPF

[denis_berthier]

Hi Coloin

Thanks for your answer,
960 M would be about 75 GB (non compressed), much too large for any place on the web. I wonder if anyone is still keeping them now.
I found a 2M collection by gsf or JPF (I lost the link).

My idea was as follows.
I've shown long ago that the mean complexity of minimal puzzles increases slowly with the clue count (however, with large variations for each fixed clue count).
For the 49,158 17-clue puzzles, the situation is very simple: they are all in T&E(0 or 1) and the hardest has relatively low W rating = 8.

I wondered if there could be 18-clue ones in T&E(2) - and indeed the answer is yes. I found 4 (in the 2M) , with their BpB classifications:

Code: Select all

..3....8..5.1....6.....2....6.7..9.......3.....4..8................34.2.91.6.....; B1B
..345............6..9.2.....7...13.8.6.............5..5......2......84...1...7...; B1B
1..........7..9..36.....45......8.........61..9...3....3....897.............6.1..; B1B
............1.92...6......4.7..4.............8.1..59...4..6...7..9........2..1..6; B2B

I now have no doubt larger values of p could be obtained with the 960M collection.
.

[m_b_metcalf]

Does this one also qualify?

Code: Select all

..............1..2..3.4.56............753.....2......8......3...1..5.7...8...2..1

Mike

[JPF]

Does this one also qualify?

Code: Select all

..............1..2..3.4.56............753.....2......8......3...1..5.7...8...2..1

Ah, yes, an excellent puzzle featured in this list!

JPF

[denis_berthier]

Does this one also qualify?

Code: Select all

..............1..2..3.4.56............753.....2......8......3...1..5.7...8...2..1

Yes, it's in B2B.

[blue]

Hi Denis,

I posted an extension to JPF's list, here.
Would you post the BpB ratiings for the ER=10.x cases, please ?

Cheers.

[denis_berthier]

Hi Denis,
I posted an extension to JPF's list, here.
Would you post the BpB ratiings for the ER=10.x cases, please ?.

Hi Blue
Nice to see you here; it's been a long time.
Here are the results for the two lists, in the same order. BpB = 0 means that the puzzle is in T&E(1).

You can see that:
- the max value of p in both lists is 2,
- it is reached in your list much more often than in JPF's,
- it is not restricted to the highest SER values (which was to be expected, as there's only a very vague correlation between SER and BpB).

Code: Select all

;;; JPF
2
1
1
1
1
1
1
0
1
2
2
1
0
1
0
1
1
1
2
1
1
0
0
1
1
1
0
0
1
0
1
0
0
0
1
1
1
1
0
0
0
0
1
0
0
0
0
1
1
;;; blue
2
2
2
2
2
2
2
2
2
2
2
2
2
1
2
2
2
2
1
2
2
1
1
1
2
2
2
1
2
2
2
2
2
2
2
2
1
1
1
2
1
1
1
2
2
1
2
1
2
2
1
1
2
1
2
1
1
1
1
1
1
1
1
1
2
1
2
1
2
2

BTW, do you have any reference to a list of 2,000,000 18c. I copied it from somewhere, but I can't find it again.
.

[blue]

Here are the results for the two lists, in the same order. BpB = 0 means that the puzzle is in T&E(1).

You can see that:
- the max value of p in both lists is 2,
- it is reached in your list much more often than in JPF's,
- it is not restricted to the highest SER values (which was to be expected, as there's only a very vague correlation between SER and BpB).

Thank you.
I thought the 10.3 might rate a little higher, after looking at the "after singles" PMs, but nope !

BTW, do you have any reference to a list of 2,000,000 18c. I copied it from somewhere, but I can't find it again.

I don't, sorry.

I have a big list, locally, with ~1.5G puzzles in it.
I extracted all of the T&E(2) puzzles from it, but there were only 780 of them.
Close to half of them were solvable with basics ... due to the bit with naked triples, I think.
I could put that list in a post, if you like ... FWIW