There are buildings in the background.
The back of the picture contains a tree and a building.
Buildings in the background does not mean there is also a tree.
exists p1 x1 x3.(n_background(x3) & exists x2.((x1 = x2) & in(x2,x3) & n_building(x2)))
exists e1 x1 x2 x3 x4 x5.(n_picture(x2) & n_back(x1) & Theme(e1,x3) & Actor(e1,x1) & v_contain(e1) & subset_of(x5,x3) & n_building(x5) & subset_of(x4,x3) & n_tree(x4) & of(x1,x2))