A yellow tractor sits on a hillside.
The farmer sits in the tractor.
A yellow tractor not necessarily implies farmer sits in the tractor.
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 e1 x1 x2.(n_tractor(x2) & n_farmer(x1) & in(e1,x2) & Actor(e1,x1) & v_sit(e1))