GokyoShumyoSection3Problem19/Attempts

solution?  

xela: This part looks simple. The interesting bit (to me) is to prove that white can't kill, and that black doesn't have a better defence.

variation  

xela: Black can not avoid ko.

failure  

xela: If white tries too hard, black ends up living unconditionally. (If is at a, it's ko again, right?)