Mathimagics wrote:Is there any correlation between lack of singles and SE rating?
Here are some 18-clue samples with (as far as I can tell), no singles at all. I don't have any rating software - it's against my religion
This is essentially how the race to find the hardest sudoku started back in 2006 ...
We started by finding the puzzles that didn't offer any singles (We called them Pearls & essentially would have a high EP rating). We then progressed to the (Diamonds) where even a single elimination wasn't available and these were puzzles with high ED ratings.
As far as I can see these puzzles would have a "busier" Starting Pencilmark grid making it more difficult to use the players conventional technique arsenal.
What it can't predict is "For how long will that Pencilmark grid remain busy?" after hitting it with a relentless set of advanced techniques. There are some techniques which are as complex as these puzzles (The advanced MSLS for instance) which break down several of these tough puzzles.
Because the "yardstick" of measuring difficulty remains debatable, you will find the most difficult puzzles end up several toughness criteria rather than being one dimensional.
Advanced players like these puzzles that attract a level of difficulty at their level as it they avoid the clutter of "Basic techniques" needed to bring the puzzle nearer to their desired interesting section.
Tarek