A seminar in an auditorium.
 A seminar in an large open auditorium.
Auditoriums come in many different sizes, not just large and open
exists x1 x2.(a_topic(x1) & in(x1,x2) & n_auditorium(x2) & n_seminar(x1))
exists s1 s2 x1 x2.(a_topic(x1) & in(x1,x2) & n_auditorium(x2) & a_open(s2) & Theme(s2,x2) & a_large(s1) & Theme(s1,x2) & n_seminar(x1))