A crowded city street.
A city street is empty.
It can't be a crowded city street if the street is empty.
exists s1 x1 x2.(a_topic(x1) & n_street(x1) & of(x1,x2) & n_city(x2) & a_crowded(s1) & Theme(s1,x1))
exists s1 x1 x2.(Theme(s1,x1) & a_empty(s1) & n_street(x1) & of(x1,x2) & n_city(x2))