A concert in a parking lot.
A concert on a rooftop.
Either the concert is in the parking lot or on the roof top.
exists x1 x2 x3.(a_topic(x1) & in(x1,x2) & n_lot(x2) & of(x2,x3) & n_parking(x3) & n_concert(x1))
exists x1 x2.(a_topic(x1) & on(x1,x2) & n_rooftop(x2) & n_concert(x1))