People smoking in a smoking area.
a bird was on rocks
A bird on rocks can be inferred if there are also people smoking in a smoking area.
exists x1 x2 x3 x4.(a_topic(x1) & in(x1,x3) & n_area(x3) & of(x3,x4) & n_smoking(x4) & n_smoking(x1) & of(x1,x2) & n_people(x2))
exists p1 x1.(exists x2.(on(x1,x2) & n_rock(x2)) & n_bird(x1))