A girl is in the surf.
A person is in the surf.
The person in the surf is a girl.  The second is a further descriptor of the first.
exists p1 x1 x2.(n_surf(x2) & in(x1,x2) & n_girl(x1))
exists p1 x1 x2.(n_surf(x2) & in(x1,x2) & n_person(x1))