a crowd of people in a subway
people at home
People can not be in a subway and at home at the same time.
exists x1 x2 x3.(a_topic(x1) & in(x1,x3) & n_subway(x3) & of(x1,x2) & n_people(x2) & n_crowd(x1))
exists x1 x2.(a_topic(x1) & at(x1,x2) & n_home(x2) & n_people(x1))