People walking across a crosswalk.
People are crossing the street.
Walking across a crosswalk does not necessarily mean crossing the street.
exists e1 x1 x2 x3.(a_topic(x1) & across(e1,x3) & n_crosswalk(x3) & Actor(e1,x2) & v_walk(e1) & (x1 = x2) & n_people(x1))
exists e1 x1 x2.(n_street(x2) & Theme(e1,x2) & Actor(e1,x1) & v_cross(e1) & n_people(x1))