After , both pairs of points a/b, and c/d, are miai for life.
For those who have solved or looked at the earlier problems in this series, this line of play will have become familiar. After , if Black connects at a, White captures three stones to make a second eye on the first line.
After then lives. If black a later on then white b is the only move to ensure two eyes.
It would be a mistake for White to answer at a (next diagram).
If at , then at , and White has only one eye.
This may be the hardest one to refute. After , White can't play at a because of shortage of liberties. If she captures at b, Black plays at a himself to make the eye false.
White at here, gives the same result as if White's first mov was played correctly at in this diagram, but White errs with her second move, by answering at (see earlier diagram: Mistake in the follow-up move from the Solution).
White lives in ko, which is not good enough.
griffin: 6 makes ko