A person standing on a ridge in the desert.
The person is in the desert.
A ridge in a desert may be at the edge of the desert, not in the desert, so the person standing on the ridge may be at the edge of the desert..
exists e1 x1 x2 x3 x4.(n_desert(x4) & a_topic(x1) & in(e1,x4) & on(e1,x3) & n_ridge(x3) & Actor(e1,x2) & v_stand(e1) & (x1 = x2) & n_person(x1))
exists p1 x1 x2.(n_desert(x2) & n_person(x1) & in(x1,x2))