Igo Hatsuyoron - Problem 120, the most difficult problem.

Chatting to T-Mark Hall (who maintains GoGoD - Games of Go on Disk) is like opening up a treasure chest of information about Go. I opened a book, and said 'oh that looks interesting' and it turned out to be the Most Difficult Problem, from a collection of Go problems called the Igo Hatsuyoron. Black to play and win:


Don't spend too long on this - it officially hasn't been solved! For more information have a look at the entry on it in Sensei's Library