People gathered together on a city street.
the street is empty
People cannot be gathered together if the street is empty.
exists e1 p1 x1 x2 x3.(on(e1,x2) & n_street(x2) & of(x2,x3) & n_city(x3) & exists s1.(Theme(s1,x1) & a_together(s1)) & Topic(e1,p1) & Actor(e1,x1) & v_gather(e1) & n_people(x1))
exists s1 x1.(n_street(x1) & Theme(s1,x1) & a_empty(s1))