A seminar in an auditorium.
 A seminar in the auditorium.
An auditorium in the same thing as the auditorium.
exists x1 x2.(a_topic(x1) & in(x1,x2) & n_auditorium(x2) & n_seminar(x1))
exists x1 x2.(n_auditorium(x2) & a_topic(x1) & in(x1,x2) & n_seminar(x1))