Cap one step ahead
A lone white stone in the open centre looks free, but it has no friend within reach — and that is all a net needs. The net (罩) never ataris: it caps one loose step ahead of the runner, sealing the escape direction without handing White a single forcing reply. Chased tightly, the stone would dodge atari after atari and gain liberties on every dodge; netted, it can only watch the exits close. Black to play: net the white stone — cap it from above.