Two ladies are walking on the road.
Nobody on the road
If two ladies are walking on the road, then there cannot be nobody on the road. There are two ladies on the road.
exists e1 x1 x2.(n_road(x2) & on(e1,x2) & Actor(e1,x1) & v_walk(e1) & n_lady(x1) & card_eq_2(x1))
exists x2.(n_road(x2) & -exists x1.(a_topic(x1) & on(x1,x2) & n_person(x1)))