A dog and a ball.
A cat is playing ball.
An animal cannot be both a dog and a cat
exists s1 x1 x2.(a_topic(s1) & subset_of(x2,s1) & n_ball(x2) & subset_of(x1,s1) & n_dog(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_ball(x2) & n_cat(x1))