## The hardest sudokus (new thread)

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

### Re: The hardest sudokus (new thread)

ronk wrote:
champagne wrote:To-day, you get the final result in about 4 hours (on my computer).

Since I'm an engineer, statements like that make my hair stand up. Everyone, is it too much to ask that execution times be normalized to ... 'T' Ghz-sec? Then the rest of us could estimate execution times on our computers by dividing 'T' by our CPU clock rate.

*You are surely right, but I guess most of us have a computer with a clock around 3MGH, so the order of magnitude should not change that much.

To be as precise as possible, I have a portable PC under vista with a double core and a clock of 2.4 GHZ (32 bits registers)

The rating was run with others programs, so the overall time could be influenced by other tasks.

Anyway, the 4 hours is a rough estimate. Could be 3 (small chances), could be 5 as well.

champagne
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### Re: The hardest sudokus (new thread)

champagne wrote:
m_b_metcalf wrote: It was 'only' 11.4 back then. I peaked early.

This puzzle is likely the highest known rating for SE.

Gosh, if true, that would make me the reigning World SE Champion!
BTW, I tried to find a start for the pattern game using that pattern, but I failed.

I tried that too.

I went back to the original pattern, as an exercise using my current s/w, rather than the antiques back then, and found a diamond and a few others you might like for your collection.
Code: Select all
`100000002030400050006000700080203000000070000000508040007000600050009080200000001   ED=10.4/10.4/10.4100000002030400050006000700040603000000020000000508090007000100080009030200000006   ED=10.5/10.5/10.4100000002030400050006000700040803000000010000000506090007000600080009030200000001   ED=10.6/10.6/10.4100000002030400050006000700040603000000020000000508090007000600080009030200000001   ED=10.7/10.7/10.4`

Of course, if JPF's brilliant pattern were presented in a Patterns Game today, the 11.8 would never be found and investigated.

Regards,

Mike Metcalf

m_b_metcalf
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### Re: The hardest sudokus (new thread)

Hi mike,

I did not work on that pattern specifically to find high rating, but looking for a game start, I got also that one

Code: Select all
`9.......5.7...4.1...3...8.....2.7.4.....3.....1.6.......8...3...6.1...7.5.......9 ED=10.8/10.8/3.4`

I will check if some of your 4 are in the general search I am doing, but I am not ready for a quick answer.

As far as I can see, nearly all puzzles generated with that pattern have the SK loop. All in your lot have it.

champagne
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### Re: The hardest sudokus (new thread)

Code: Select all
`Rating: 11.9  (ER/EP/ED=11.9/11.9/11.3)Poster: tarek Label: golden nugget `

They all have the SK loop because the 16-clue base [without the central box with 4 clues] - inherently tends to have a low solution count - because some eliminations can be made with just those 16 clues.....

Puzzles which dont have a relatively low solution count with a selection of 16-clues - dont have the SK loop.

But if you dont have the low solution count - there are fewer ways to add a few clues to make a puzzle.

C
coloin

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### Re: The hardest sudokus (new thread)

coloin wrote:
Code: Select all
`Rating: 11.9  (ER/EP/ED=11.9/11.9/11.3)Poster: tarek Label: golden nugget `

They all have the SK loop because the 16-clue base [without the central box with 4 clues] - inherently tends to have a low solution count - because some eliminations can be made with just those 16 clues.....

Puzzles which dont have a relatively low solution count with a selection of 16-clues - dont have the SK loop.

But if you dont have the low solution count - there are fewer ways to add a few clues to make a puzzle.

C

I agree on Golden Nugget rating. I had it, but I did not keep in ming the results, may-be because I was impressed by the "relative poor rating" for Silver Plate : ED=11.5/11.5/10.1

Regarding the SK loop, I have another way to look at it.

All examples of the SK loop I analyzed have a common piece of pattern :

- four given forming a rectangle in four boxes
- all cells in rows/columns/boxes for this rectangle unknown.

If you have that piece of pattern, then, you have a reasonable chance to find a SK loop.

champagne
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### Re: The hardest sudokus (new thread)

coloin wrote:
Code: Select all
`Rating: 11.9  (ER/EP/ED=11.9/11.9/11.3)Poster: tarek Label: golden nugget `

So, tarek has the Title!

Congrats.

Mike Metcalf
Last edited by m_b_metcalf on Tue Aug 24, 2010 11:33 am, edited 1 time in total.

m_b_metcalf
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champagne wrote:I did not work on that pattern specifically to find high rating, but looking for a game start, I got also --
Code: Select all
`9.......5.7...4.1...3...8.....2.7.4.....3.....1.6.......8...3...6.1...7.5.......9 ED=10.8/10.8/3.4`
As far as I can see, nearly all puzzles generated with that pattern have the SK loop.

looking for a game start ?
so now, the challenge is to find an easy puzzle with this pattern ?

Pat

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### Re: The hardest sudokus (new thread)

champagne wrote:... looking for a game start, I got also that one
Code: Select all
`9.......5.7...4.1...3...8.....2.7.4.....3.....1.6.......8...3...6.1...7.5.......9 ED=10.8/10.8/3.4`

And there are these too:
Code: Select all
`1.......2.3...4.5...6...7.....8.3.4.....6.....5.9.......7...6...8.5...3.2.......1   ED=10.7/10.7/3.4 1.......2.3...4.5...6...7.....5.3.4.....1.....8.9.......7...6...9.8...3.2.......1   ED=11.6/11.6/3.4 `

Regards,

Mike Metcalf

m_b_metcalf
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### Re: The hardest sudokus (new thread)

The Guardian published this puzzle this week:
http://www.guardian.co.uk/media/2010/au ... ed-picture
I don't know if it's one of yours, or how it compares!
ab

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### Re: The hardest sudokus (new thread)

ab wrote:The Guardian published this puzzle this week:
http://www.guardian.co.uk/media/2010/au ... ed-picture
I don't know if it's one of yours, or how it compares!

1) that puzzle was not in my data base.

2) In a pattern game (that could not happen due to the fact that the puzzle has not the symmetry requirements), i would likely have rated it.

3) The SE rating for that puzzle is 10.6 1.2 1.2 which is not bad

4) it has no special pattern (SK loop, EXOCET) and I found no rank0 logic

5) seen by my solver
it enters level 3 of tagging
both run time and print size put it limit down to enter the family of hardest.
The most difficult step uses 3 cycles of derived links

Surely an interesting puzzle for skill players as "ttt" or stevek

champagne
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### Re: The hardest sudokus (new thread)

ab wrote:The Guardian published this puzzle this week:
http://www.guardian.co.uk/media/2010/au ... ed-picture
I don't know if it's one of yours, or how it compares!

Not in my database either, so it's probably not a puzzle previously known to this forum.
ronk
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### Re: The hardest sudokus (new thread)

ab wrote:The Guardian published this puzzle this week:
http://www.guardian.co.uk/media/2010/au ... ed-picture
I don't know if it's one of yours, or how it compares!

looks like Arto has a 15-minutes-of-fame generator
and the media bites every time
gsf
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### Re: The hardest sudokus (new thread)

Strange how Arto Inkala's puzzles get a lot of attention from the media whereas none of the other puzzles in this thread do. I wonder how much the media paid for it.
999_Springs

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### Re: The hardest sudokus (new thread)

999_Springs wrote:Strange how Arto Inkala's puzzles get a lot of attention from the media whereas none of the other puzzles in this thread do. I wonder how much the media paid for it.

most surprising is that somebody can claim to have found "the hardest puzzle" publishing something similar to what each of the pattern game players generates every week.

The "hardest puzzles" published in that forum have been found 2 or 3 years ago !!!!
They are about ten times harder than that one.

champagne
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### Re:

Pat wrote:
champagne wrote:I did not work on that pattern specifically to find high rating, but looking for a game start, I got also --
Code: Select all
`9.......5.7...4.1...3...8.....2.7.4.....3.....1.6.......8...3...6.1...7.5.......9 ED=10.8/10.8/3.4`
As far as I can see, nearly all puzzles generated with that pattern have the SK loop.

looking for a game start ?
so now, the challenge is to find an easy puzzle with this pattern ?

Here are two possible starts, though it would not be an interesting game.
Code: Select all
`1.......2.3...4.5...2...6.....6.2.4.....7.....5.8.......6...4...8.3...7.2.......11.......2.3...4.5...2...6.....6.7.8.....3.....9.2.......6...9...4.9...3.7.......1`
Mauricio

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