Small boy walking towards the left, with the bases of trees in the back.
A small boy is in front of trees.
The trees are described as being in the back, or behind the small boy, and in the second sentence the boy is describe as being in front of them.
exists e1 s1 x1 x2 x3 x4 x5 x6.(n_back(x6) & n_basis(x4) & n_left(x3) & a_topic(x1) & towards(e1,x3) & with(x3,x4) & of(x4,x5) & in(x5,x6) & n_tree(x5) & Actor(e1,x2) & v_walk(e1) & (x1 = x2) & n_boy(x1) & a_small(s1) & Theme(s1,x1))
exists p1 s1 x1.(exists x2 x3.(in(x1,x2) & of(x2,x3) & n_tree(x3) & n_front(x2)) & n_boy(x1) & a_small(s1) & Theme(s1,x1))