eleven wrote:Look at the pair 59 in column 9 (you have used it in the box only). Another pair then can solve it.
Ah, there is typo in r3c9, there wasn't supposed to be 9 inside.
Oh wait, do you mean that from r7c9 and r9c9, and then r1c1 and r9c1, the 59-pairs force r6c1 to be 8? That'd be correct answer, I'm just not sure about the logic if it works or not??
I'd really like to learn how to solve these really difficult ones, I'm just not there yet
tpatana wrote:I tried few online solvers...
There should be better ones, but i dont have links. Two good (and free) programs, which can help you also for harder puzzles are
Sudoku Explainer and
JSudoku.
Thanks for these, I'll have to take a look.