A man rock climbing.
A man is on top of a rock.
A man rock climbing is not necessarily on top of a rock.
exists e1 x1 x2 x3.(a_topic(x1) & Actor(e1,x3) & v_climb(e1) & (x1 = x3) & n_rock(x1) & of(x1,x2) & n_man(x2))
exists p1 x1.(exists x2 x3.(on(x1,x2) & of(x2,x3) & n_rock(x3) & n_top(x2)) & n_man(x1))