Very Artificial Problem
A few weeks ago, a 3 dan at our club showed us the following entirely artificial, but rather difficult problem:
Black to capture white with two stones
I've been trying for hours, but still haven't found a solution of this very artificial problem. I guess I am missing a few tesuji on Black's part, because I can always find a way for White to live or escape.
The guy who showed us the problem didn't tell us the solution, and nobody could figure it out so far. The most popular solution is saying that it is a stupid problem because nobody would ever play like this anyway ;-)
It's very not dumb, really, in that computers would need to work through this kind of thing when looking to make a perfect player.