several people at an airport.
The people are alone.
The people can either be at an airport or alone. They cannot be alone if there are several of them.
exists s1 x1 x2.(a_topic(x1) & at(x1,x2) & n_airport(x2) & n_people(x1) & a_several(s1) & Theme(s1,x1))
exists s1 x1.(n_people(x1) & Theme(s1,x1) & a_alone(s1))