Lonestar: I think the solution must be the play at .
DomQ If black attempts to form an extra eye this way, his hope is ruined by a snapback ! If Black plays a then White plays 5 again, capturing the circled stones.
fivebells?, beginner: This may be obvious to others, but I came over here to ask whether the hane at works, and determined why it doesn't while writing my reasoning out: After black a, b and c are miai for an eye, and black is already guaranteed one eye by a play at d or e.