A girl rides a horse.
A small girl rides her horse
A girl riding a horse does not necessarily imply that it is her horse.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_horse(x2) & n_girl(x1))
exists e1 s1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_horse(x2) & of(x2,x1) & n_female(x1) & n_girl(x1) & a_small(s1) & Theme(s1,x1))