A baby in a cart on a sidewalk.
A teenager in a box on a sidewalk.
A baby is not the same as a teenager.
exists x1 x2 x3.(a_topic(x1) & in(x1,x2) & on(x2,x3) & n_sidewalk(x3) & n_cart(x2) & n_baby(x1))
exists x1 x2 x3.(a_topic(x1) & in(x1,x2) & on(x2,x3) & n_sidewalk(x3) & n_box(x2) & n_teenager(x1))