A family picture
It is a picture of the president.
The picture of a president is not a family photo.
exists x1 x2.(a_topic(x1) & n_picture(x1) & of(x1,x2) & n_family(x2))
exists p1 x1 x3.(n_president(x3) & n_thing(x1) & exists x2.((x1 = x2) & of(x2,x3) & n_picture(x2)))