A bird perches in an empty window frame.
A bird is close by a window frame.
empty window frame  is the same as window frame.
exists e1 s1 x1 x2 x3.(in(e1,x2) & n_frame(x2) & of(x2,x3) & n_window(x3) & a_empty(s1) & Theme(s1,x2) & Actor(e1,x1) & v_perch(e1) & n_bird(x1))
exists s1 x1 x2 x3.(by(s1,x2) & n_frame(x2) & of(x2,x3) & n_window(x3) & Theme(s1,x1) & a_close(s1) & n_bird(x1))