A dog runs through the grass.
dog chasing rabbit
The dog may not be chasing anything, and if he is it may not be a rabbit.
exists e1 x1 x2.(n_grass(x2) & through(e1,x2) & Actor(e1,x1) & v_run(e1) & n_dog(x1))
exists x1 x2 x3.(n_rabbit(x1) & of(x1,x3) & n_chasing(x3) & of(x1,x2) & n_dog(x2) & a_topic(x1))