People stroll outdoors at the airport.
People are walking by an airport
people strolling outside airport does not imply they are walking
exists e1 x1 x2 x3.(n_airport(x3) & at(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_stroll(e1) & n_outdoors(x2) & n_people(x1))
exists e1 x1 x2.(by(e1,x2) & n_airport(x2) & Actor(e1,x1) & v_walk(e1) & n_people(x1))