A child is placing an item on a red wall.
The child was by a red wall.
A child placing an item on a red wall doesn't mean they are by it.
exists e1 s1 x1 x2 x3.(on(e1,x3) & n_wall(x3) & a_red(s1) & Theme(s1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_place(e1) & n_item(x2) & n_child(x1))
exists p1 x1.(n_child(x1) & exists s1 x2.(by(x1,x2) & n_wall(x2) & a_red(s1) & Theme(s1,x2)))