A little boy swims underwater.
A little boy swimming at a beach.
Not all little boys who swim underwater do so at a beach.
exists e1 s1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_swim(e1) & n_underwater(x2) & n_boy(x1) & a_little(s1) & Theme(s1,x1))
exists s1 x1 x2 x3.(a_topic(x1) & at(x1,x3) & n_beach(x3) & n_swimming(x1) & of(x1,x2) & n_boy(x2) & a_little(s1) & Theme(s1,x1))