Two women are looking at a tower.
Nobody is looking.
A space can't be occupied by nobody and two someones at the same time.
exists e1 x1 x2.(at(e1,x2) & n_tower(x2) & Actor(e1,x1) & v_look(e1) & n_woman(x1) & card_eq_2(x1))
-exists e1 x1.(Actor(e1,x1) & v_look(e1) & n_person(x1))