VanEvery - Shouldn't Black play at instead? Since the status is settled after , it seems a complete waste to put a third move into this. What is the value of where it is?
Dieter: This is a failure diagram. It serves to show that Black does not kill White this way but achieves at most seki. Discussing the merits of and is irrelevant for this problem, since was wrong to start with and - are merely the functional follow-up to the mistake was.