A yellow tractor sits on a hillside.
A tractor on a farm.
A tractor on a hillside is not necessarily on a farm.
exists e1 s1 x1 x2.(on(e1,x2) & n_hillside(x2) & Actor(e1,x1) & v_sit(e1) & n_tractor(x1) & a_yellow(s1) & Theme(s1,x1))
exists x1 x2.(a_topic(x1) & on(x1,x2) & n_farm(x2) & n_tractor(x1))