A woman laughing by a lake.
A woman is on vacation at the lake.
A woman is by a lake but it doesn't mean she is on vacation.
exists e1 x1 x2 x3.(a_topic(x1) & by(e1,x3) & n_lake(x3) & Actor(e1,x2) & v_laugh(e1) & (x1 = x2) & n_woman(x1))
exists p1 x1 x2.(n_lake(x2) & at(p1,x2) & exists x3.(on(x1,x3) & n_vacation(x3)) & n_woman(x1))