People stroll outdoors at the airport.
People are walking outside the airport.
If you stroll you are walking and if you are outdoors you are outside.
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.(n_airport(x2) & outside(e1,x2) & Actor(e1,x1) & v_walk(e1) & n_people(x1))