A young boy plays on a swing.
A young boy plays.
in both sentences, a young boy plays.
exists e1 s1 x1 x2.(on(e1,x2) & n_swing(x2) & Actor(e1,x1) & v_play(e1) & n_boy(x1) & a_young(s1) & Theme(s1,x1))
exists s1 x1 x2.(a_topic(x1) & n_play(x1) & of(x1,x2) & n_boy(x2) & a_young(s1) & Theme(s1,x1))