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"the World's hardest logic/number puzzles"
http://www.calcudoku.org/forum/viewtopic.php?f=24&t=463
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Author:  pnm  [ Fri Jul 05, 2013 10:34 am ]
Post subject:  "the World's hardest logic/number puzzles"

Ok, my write-up is in a state where it can be published, I think:

http://www.calcudoku.org/hardest_logic_number_puzzles

Check it out, feedback very welcome, and do like/tweet/etc... :-)

Author:  pnm  [ Fri Jul 05, 2013 10:37 am ]
Post subject:  Re: "the World's hardest logic/number puzzles"

And please vote up:
http://www.reddit.com/r/sudoku/comments ... er_puzzles

And if you have a Slashdot account, vote up here:
http://slashdot.org/recent

[thumbup]

Author:  pnm  [ Fri Jul 05, 2013 10:50 pm ]
Post subject:  Re: "the World's hardest logic/number puzzles"

pnm wrote:
Check it out, feedback very welcome, and do like/tweet/etc... :-)

Alright, that didn't work really.

Picked up nowhere, hardly any likes/tweet, no reaction anywhere [sad]

Perhaps the topic isn't sufficiently accessible?
For example, one puzzle publisher I know wrote
that they only cater to average puzzlers, so stories
like this are not interesting [mellow]

Author:  picklepep  [ Sat Jul 06, 2013 5:17 pm ]
Post subject:  Re: "the World's hardest logic/number puzzles"

I found it interesting, and I checked out a few of the puzzles, But didn't try to actually solve them. If I ever have a free weekend I might actually tackle one of them.(Or maybe a long plane ride)

Author:  pnm  [ Tue Jul 09, 2013 11:48 am ]
Post subject:  Re: "the World's hardest logic/number puzzles"

nicow sent me this puzzle from killersudokuonline.com,
which most likely is a lot harder than the one I've put up:

Image

(my solver is still chewing on it, running for 20 minutes already..)

What do people think of this puzzle? Of course a puzzle can always
be made harder (including this one), while it's still possible to solve
it analytically, but of course we do want to stay in the realm of "puzzles
realistically solvable by humans".

Author:  clm  [ Wed Jul 10, 2013 9:09 pm ]
Post subject:  Re: "the World's hardest logic/number puzzles"

pnm wrote:
nicow sent me this puzzle from killersudokuonline.com,
which most likely is a lot harder than the one I've put up:

...

(my solver is still chewing on it, running for 20 minutes already..)

What do people think of this puzzle? Of course a puzzle can always
be made harder (including this one), while it's still possible to solve
it analytically, but of course we do want to stay in the realm of "puzzles
realistically solvable by humans".


I have solved this KS and yes, it's much more difficult than the previous one you were showing in the topic (a lot of analysis is necessary and it takes a lot of time) so, IMHO, you could include it (for the moment [smile], sure we will soon deal with another more difficult) in your list.

Here we find many big cages: 2 cages of 8-cell, 1 of 7-cell, 4 of 6-cell, 4 of 5-cell, and the "easier" 2 of 3-cell and 4 of 2-cell. The puzzle has a unique solution and complies with the rule of non-repetition of numbers inside a cage being this condition a guide to the solution, for instance, since the cage "42" can not contain a 3, a 3 must be in g7 or g8 and this cooperates to determine the pair f3-d7 once we have obtained that f3 + d7 = 7 using the standard calculus for innies and outies, etc..

Author:  pnm  [ Wed Jul 10, 2013 9:21 pm ]
Post subject:  Re: "the World's hardest logic/number puzzles"

clm wrote:
I have solved this KS and yes, it's much more difficult than the previous one you were showing in the topic (a lot of analysis is necessary and it takes a lot of time) so, IMHO, you could include it (for the moment [smile], sure we will soon deal with another more difficult) in your list.

Yes, in my opinion you can take any puzzle and modify it slightly to make it even more difficult.

So for now I'll probably change the item header to "One of the Hardest Killer Sudoku Puzzles" :-)

Author:  pnm  [ Thu Aug 08, 2013 4:17 pm ]
Post subject:  Re: "the World's hardest logic/number puzzles"

So far I've had two reactions wrt. the Killer Sudoku puzzle, one pointing
me to a puzzle at killersudokuonline.com (published 21/12/2012), which was indeed much harder
(image provided by this user):

Image

The 2nd reaction pointed me to the "super tough" puzzles by "krazydad":

http://www.krazydad.com/killersudoku/sf ... T_8_v1.pdf

This user stated that the Killer Sudoku at http://www.calcudoku.org/hardest_logic_ ... es/#killer
was "a joke" and "ridiculously easy", and the "real stuff" was on krazydad's site.

Oddly though, I ran both puzzles 1 and 8 through my solver, and found that
puzzle 1 was of a medium difficulty, and puzzle 8 was indeed very difficult (but comparable
to the one I put up).

So now I'm thinking: did I miss some kind of solution step that made my puzzle
indeed ridiculously easy?

Any feedback much appreciated...

Patrick

Author:  clm  [ Thu Aug 08, 2013 9:19 pm ]
Post subject:  Re: "the World's hardest logic/number puzzles"

pnm wrote:
So far I've had two reactions wrt. the Killer Sudoku puzzle, one pointing
me to a puzzle at killersudokuonline.com (published 21/12/2012), which was indeed much harder
(image provided by this user):
...
The 2nd reaction pointed me to the "super tough" puzzles by "krazydad":
...
This user stated that the Killer Sudoku at http://www.calcudoku.org/hardest_logic_ ... es/#killer
was "a joke" and "ridiculously easy", and the "real stuff" was on krazydad's site.

Oddly though, I ran both puzzles 1 and 8 through my solver, and found that
puzzle 1 was of a medium difficulty, and puzzle 8 was indeed very difficult (but comparable
to the one I put up).

So now I'm thinking: did I miss some kind of solution step that made my puzzle
indeed ridiculously easy?

Any feedback much appreciated...

Patrick


Well, the puzzle at killersudokuonline.com (which is the same nicow had sent and you posted on July 09) is really difficult, I made some comments on it when I solved it on July 10 (it took me several hours). BTW, finally, how long did your solver take to complete the solution? (the last info was that the PC was still running after 20 minutes :-) :-)).

I have just solved the puzzle #8 from this krazydad pool (the solutions are given at the end of that document), it took more or less the same time (on paper) that your difficult's (thursdays to saturdays) on-line.

Solutioning a puzzle has always a subjective component (it shouldn't be but it's unavoidable) but I totally disagree with the person commenting that your difficult ones are "a joke" and "ridiculously easy", and that the "real stuff" is on krazydad's site. My opinion (already given in another place in this Forum, probably when discussing on Kakuros) is that the krazydad page does not contain at all outrageous puzzles, neither in Sudokus, Kakuros, etc., perhaps from medium to difficult being generous (according to my previous experience: a few years ago I made many different puzzles from krazydad and I never found great difficulties).

To increase the difficulty of the KS's (if this is your purpose) you should increase the size of the cages (like in the one from killersudokuonline.com), and you shoud avoid an easy location of any individual number (via innies and outies, etc.).

For instance, in this puzzle, the only number that can initially be placed is the 3 in a9. The reason is that (looking to nonet 9) since a 3 cann't go in an 8-cell "42" cage (it's the only number is not part of the cage), and of course is not in the "23" cage, it must be in g7 or h7; now this forces the 3 of nonet 8 to be in d8 or e8 and, since a number cann't be repeated inside any cage, another 3 cann't be in the "21" cage, in b9 or c9, so necessarily a9 = 3.

Author:  pnm  [ Thu Aug 08, 2013 9:32 pm ]
Post subject:  Re: "the World's hardest logic/number puzzles"

clm wrote:
Well, the puzzle at killersudokuonline.com (which is the same nicow had sent and you posted on July 09) is really difficult, I made some comments on it when I solved it on July 10 (it took me several hours). BTW, finally, how long did your solver take to complete the solution? (the last info was that the PC was still running after 20 minutes :-) :-)).

Ah, right, I had forgotten I had already posted that one.

I'll look up the stats on it (I think I aborted the solver after about an hour,
thinking I'm missing a solving strategy)

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