People are walking across the street of a city.
There are people sitting
Walking is in direct contradiction to sitting.
exists e1 x1 x2 x3.(n_street(x2) & across(e1,x2) & of(x2,x3) & n_city(x3) & Actor(e1,x1) & v_walk(e1) & n_people(x1))
exists p1 x1 e1 x2 x3.((x1 = x2) & Actor(e1,x3) & v_sit(e1) & (x2 = x3) & n_people(x2))