The bike is secured to a metal post.
The metal post is at a school yard.
We do not know if the post is at a school yard.
exists e1 x1 x2 x3.(n_bike(x1) & to(e1,x2) & n_post(x2) & of(x2,x3) & n_metal(x3) & Theme(e1,x1) & v_secure(e1))
exists p1 x1 x2.(n_post(x1) & of(x1,x2) & n_metal(x2) & exists x3 x4.(at(x1,x3) & n_yard(x3) & of(x3,x4) & n_school(x4)))