A person on a red bike.
the person is on a spaceship
Bike and spaceship are different.
exists s1 x1 x2.(a_topic(x1) & on(x1,x2) & n_bike(x2) & a_red(s1) & Theme(s1,x2) & n_person(x1))
exists p1 x1.(n_person(x1) & exists x2.(on(x1,x2) & n_spaceship(x2)))