young people on stage in front of an audience.
There are old people on stage.
young people cannot be old people.
exists s1 x1 x2 x3 x4.(a_topic(x1) & in(x1,x3) & of(x3,x4) & n_audience(x4) & n_front(x3) & on(x1,x2) & n_stage(x2) & n_people(x1) & a_young(s1) & Theme(s1,x1))
exists p1 x1 x2.(on(p1,x2) & n_stage(x2) & exists s1 x3.((x1 = x3) & n_people(x3) & a_old(s1) & Theme(s1,x3)))