A woman is walking her dog.
A woman and a dog.
If a woman is walking her dog, she has the dog with her, so there can be a woman and a dog.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_walk(e1) & n_dog(x2) & of(x2,x1) & n_female(x1) & n_woman(x1))
exists s1 x1 x2.(a_topic(s1) & subset_of(x2,s1) & n_dog(x2) & subset_of(x1,s1) & n_woman(x1))