A dog retrieves a golf ball.
A dog catches a frisbee.
A ball is round. A frisbee is flat.
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 x2.(Theme(e1,x2) & Actor(e1,x1) & v_catch(e1) & n_frisbee(x2) & n_dog(x1))