OD1P - Aug 4 Problem / Solution

Black gets a ko  

7 at 3.

I'm still very new to go, but from what I see this isn't really ko. No matter where White plays next, Black plays at a or b and removes the possibility of ko. Maybe my understanding of ko is wrong, but from what I gather, it's a stiuation where each side can capture a territory over and over, but must play somewhere else before they capture back. If White plays at b, Black plays at a and captures two stones, removing the ko situation. The only way I see this as a ko situation is if Black is blind. If I'm wrong on this please let me know.

SAS: It is a ko situation, but White has to find the first ko threat. So you are correct that Black can live whatever White does next - but the point is that this would mean ignoring White's ko threat, which Black may not want to do.