A person rides a dirt bike.
The dirt biker is a zombie.
person and zombie are not the same.
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & of(x2,x3) & n_dirt(x3) & n_person(x1))
exists p1 x1 x2.(n_biker(x1) & of(x1,x2) & n_dirt(x2) & exists x3.((x1 = x3) & n_zombie(x3)))