A black dog runs on the beach.
A dog runs after a ball on the beach.
Just because a dog is running on the beach does not mean he is going after a ball.
exists e1 s1 x1 x2.(n_beach(x2) & on(e1,x2) & Actor(e1,x1) & v_run(e1) & n_dog(x1) & a_black(s1) & Theme(s1,x1))
exists e1 x1 x2 x3.(n_beach(x3) & after(e1,x2) & on(x2,x3) & n_ball(x2) & Actor(e1,x1) & v_run(e1) & n_dog(x1))