A dog retrieves a golf ball.
A dog is playing
A dog that retrieves a golf ball is definitely playing.
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_retrieve(e1) & n_ball(x2) & of(x2,x3) & n_golf(x3) & n_dog(x1))
exists e1 x1.(Actor(e1,x1) & v_play(e1) & n_dog(x1))