A child on a swing.
An old lady on a swing.
Lady and child are different.
exists x1 x2.(a_topic(x1) & on(x1,x2) & n_swing(x2) & n_child(x1))
exists s1 x1 x2.(a_topic(x1) & on(x1,x2) & n_swing(x2) & n_lady(x1) & a_old(s1) & Theme(s1,x1))