Many people are walking along a sidewalk.
People are running down a street.
People cannot be walking and running simultaneously.
exists e1 x1 x2.(along(e1,x2) & n_sidewalk(x2) & Actor(e1,x1) & v_walk(e1) & n_people(x1) & n_quantity(x1))
exists e1 x1 x2.(down(e1,x2) & n_street(x2) & Actor(e1,x1) & v_run(e1) & n_people(x1))