SpAce wrote: I guess that means ArtoI can make any claims he wants as long as he makes it clear that he's using his own ranking system which is just one of many.
Do i really have to repeat myself ? Arto's sin was, that he did not publish his rating system (a big sin for a mathematician). You can be very sure, that also according to that a lot of forum puzzles were harder.
It is not true, that ratings are just a matter of taste, especially not for very hard puzzles. What has been done here was to investigate, how hard puzzles are to solve, which are high rated from this or that rating system.
PS: You might have noticed, that champagne calls his list "potentially hardest puzzles". We are all aware, that there can be different points of view. But you can be sure, that a rating, which suggests, that a puzzle is the hardest, which is not top 1000 in this list, is not trustable.