People walks on a city sidewalk.
An newspaper blows down an empty sidewalk
There can be either people walking on a sidewalk or an empty sidewalk.
exists e1 x1 x2 x3.(on(e1,x2) & n_sidewalk(x2) & of(x2,x3) & n_city(x3) & Actor(e1,x1) & v_walk(e1) & n_people(x1))
exists s1 x1 x2 x3.(a_topic(x1) & down(x1,x3) & n_sidewalk(x3) & a_empty(s1) & Theme(s1,x3) & n_blow(x1) & of(x1,x2) & n_newspaper(x2))