Two puppies pulling on a string.
Two puppies are digging in the dirt.
Dogs cannot be digging while pulling on a string.
exists e1 x1 x2 x3.(a_topic(x1) & on(e1,x3) & n_string(x3) & Actor(e1,x2) & v_pull(e1) & (x1 = x2) & n_puppy(x1) & card_eq_2(x1))
exists e1 x1 x2.(n_dirt(x2) & in(e1,x2) & Actor(e1,x1) & v_dig(e1) & n_puppy(x1) & card_eq_2(x1))