The marked black group is unsettled. If Black plays at x he makes two eyes. But if White plays there, Black would only get one eye, so the group would be dead.

	This black group is already dead. There's no room for a nose, and nowhere to make a second eye.
	This black group is alive. White can't play on either of the empty points, because that would be suicide. The marked black stone is a nose!
	This black group is alive too. It's the white stone on the inside that's dead!

1 November 2003