The New Sudoku Players' Forum

[Pupp]

I have the 49K 17_Clue puzzles file, if anybody wants. Not really sure how to save it online without it expiring after X months, or paying for a service so it's online as long as I pay for a subscription.

Right now, it doesn't seem to be hosted anyplace. I'd hate to have those puzzles to disappear from the internet.

I'm open for suggestions.

If there are any other files that seem to have disappeared off the internet, that had links from this forum in the last couple years, let me know. I'll check to see if I have any of them.

[1to9only]

[deleted] - Links are alledgedly dead! But of course they're not!! Don't want to waste more time on this!!!

[Pupp]

See: http://forum.enjoysudoku.com/17-clue-puzzles-t39364.html

Those are all dead links. lol. That's the whole point of trying to get the puzzles hosted online somehow.

Also, I downloaded the Sudoku Exchange dump (4 files, 2M+ puzzles) and converted it into .sdm files.

I used Windows Powershell to data mine the 81 digit string and copy those into a new file.

Insanely fast to be honest, each file was done by the time clicked around my desktop to find the Explorer windows the .txt files were in.

Sudoku Exchange doesn't seem to have any way to contact the site owner.

[nazaz]

Great idea to make these puzzles generally available.

I'm open for suggestions.

You could split the text file into 8 or 9 chunks then upload onto pastebin. Make sure beforehand that you pick a series of filenames that are Google-searchable like "site:pastebin.com sudoku17".

Did I read somewhere that a comprehensive search for all 17's was underway?

[denis_berthier]

Did I read somewhere that a comprehensive search for all 17's was underway?

The original exhaustive search has been done long ago. What's underway is a replication of it (always good to have a confirmation of a result).

[JPF]

The original exhaustive search has been done long ago. What's underway is a replication of it (always good to have a confirmation of a result).

No.
The only exhaustive search was done for the 16s by Gary McGuire et al. see here

The current known 17s list is the result of many contributors work.
That list was initiated and had been maintained by Gordon Royle for a long period of time.
Most of the 17s found were the result of vicinity search. There is no evidence that the current list (49158 17-clue puzzles) is complete.

The work currently done by champagne et al. is an exhaustive search for 17s.
I should let champagne explain the nature and the work he is doing on this subject.

JPF

[denis_berthier]

The original exhaustive search has been done long ago. What's underway is a replication of it (always good to have a confirmation of a result).

No.
The only exhaustive search was done for the 16s by Gary McGuire et al. see here

Ah, right. I confused the 16s and 17s.

[champagne]

The original exhaustive search has been done long ago. What's underway is a replication of it (always good to have a confirmation of a result).

No.
The only exhaustive search was done for the 16s by Gary McGuire et al. see here

The current known 17s list is the result of many contributors work.
That list was initiated and had been maintained by Gordon Royle for a long period of time.
Most of the 17s found were the result of vicinity search. There is no evidence that the current list (49158 17-clue puzzles) is complete.

The work currently done by champagne et al. is an exhaustive search for 17s.
I should let champagne explain the nature and the work he is doing on this subject.

JPF

Hi JPF,

The major findings in the 17 clues search are due to blue's work. He is also the finder of the last known 17 #49158.
In fact, thru deep vicinity search (last known by me is a +-3 vicinity done several years ago by mladen dobrichev with no positive result), the list of 17s is supposed to be nearly exhaustive, with a possible one or 2 17s missing.( 'against blue's estimate)

At this point, the only possibility to assess that we know all 17s is a full scan of the solution grids, similar to what Gary Mc Guire did on the 16 clues.

Blue proposed a new way to do this, but never disclosed the corresponding code, although he gave many clues in private messages on the strategy used.

I worked with him and started the scan with a first pass looking for 17s having one band or stack with more than 6 clues. The corresponding scan is over for years.

The last pass was to scan the solution grids for 17s having not more than 6 clues in bands and stacks.

This is the ongoing search, with an end expected by the end of this semester.

All this is heavily discussed here

Gary Mc Guire worked with 820 cores and it took him one year to establish that there was no 16 clues puzzles.

to-day, we have only below 40 cores dedicated to the scan, with I hope 15-20 more in the near future.

About 80% of the scan has been covered with no new 17.

To give more information in this field, "blue" still made huge progress in the search of low clues in solution grids.

Our friend "mathimagics", one of the contributor to the current scan (the possible newcomer is "mith") has a project to qualify solution grids having a 18 clues.
He has in hands a DLL from blue having amazing good results; Unhappily, again, we don't have the sources, and blue is not active to-day.
I am trying to crack the last ideas of blue, or to reached a similar performance. A true challenge.