Pupp wrote:Thanks. Just curious, but does anybody know the highest difficulty for normal sudoku puzzles they use in competition?
There has to be some sort of upper bound, since solvers have a time limit to solve a puzzle.
the thing about speed solving sudoku puzzles is that once you get beyond a certain difficulty level it is much faster to guess-and-check and rub out your numbers if you guessed wrong. the general consensus in the puzzle solving world is that this point happens at pairs/triples and x-wings and maybe swordfish, which would be a maximum se rating of 4.0. some people use uniqueness too, which would move it up to the 4.5 range
puzzles above this, such as the puzzles in the puzzles section of this forum which are in the 7 range, would not typically be considered suitable for speed solving. if you were to speed solve those you would always either guess and hope you got it right, or do a bifurcation from a certain point until you get a contradiction but not in the way the people posting here use wings or als's or aic's with their fancy notation. they would not consider our solutions to those puzzles here as "beautiful" in the same way we do. beyond this, puzzles in the 8 range would not even be considered as valid sudokus at all
i have a friend who is a speed solver and i had a facebook conversation with him on this topic a couple of years ago and this is what he said
There are some (notably Thomas Snyder aka motris) who believe that locked sets and X wings are the limit. Some people agree with him in principle but not about where the line is.
Some people believe that bifurcation is a valid strategy and that contests should have puzzles that test your ability to choose a useful guessing point and find contradictions.
These camps disagree vehemently. Thomas Snyder boycotted competitions for years because the other camp was winning. He's come back now that most people are on his side (having so many novel variants made it easier to stick to simpler techniques, but some variants obviously make certain techniques easy(ier) that are normally difficult in standard puzzles and some have their own set and so on...)
But there are still a few people (mostly central Europeans like the Czechs the Slovaks and the Slovenes) who like guessing puzzles
So it pays to know who's who when solving because the author might be in the guessing camp
(thomas snyder was the world champion for a few years i think)
also for some reason the speed solving community absolutely hate platinum blonde (se 10.6? I don't remember exactly) and use that puzzle as an example to poke fun at "purist" sudoku solving communities, like this one, who value hard puzzles for their own sake. I have no idea why they picked platinum blonde and neither does my friend, but he says there is a frequently quoted line that goes "I'd rather do a pretty (insert variant) than platinum blonde" with the underlying idea that people who like doing puzzles at this difficulty level are delusional and wasting their time. this particular puzzle has become a bit of a meme
maybe strmckr could shed some more light on this topic
edit:
tarek wrote:I’m not sure where to find it now but somebody has a thread with puzzles having the maximal number of clues for each SE rating which is impressive
Tarek
I'm just a "somebody"?
alright from now on I'll refer to you as "somebody" and see how you like it 
