A boy swings in the air.
The boy is on a swing.
A person can swing in the air using devices other than a swing.
exists x1 x2 x3.(n_air(x3) & a_topic(x1) & in(x1,x3) & n_swing(x1) & of(x1,x2) & n_boy(x2))
exists p1 x1.(n_boy(x1) & exists x2.(on(x1,x2) & n_swing(x2)))