Children playing on rocks.
There are children playing.
Children who are playing on rocks are playing.
exists e1 x1 x2 x3.(a_topic(x1) & on(e1,x3) & n_rock(x3) & Actor(e1,x2) & v_play(e1) & (x1 = x2) & n_child(x1))
exists p1 x1 e1 x2 x3.((x1 = x2) & Actor(e1,x3) & v_play(e1) & (x2 = x3) & n_child(x2))