A man is standing behind a giant green machine.
A man is standing by a machine
standing by refers to standing behind.
exists e1 s1 s2 x1 x2.(behind(e1,x2) & n_machine(x2) & a_green(s2) & Theme(s2,x2) & a_giant(s1) & Theme(s1,x2) & Actor(e1,x1) & v_stand(e1) & n_man(x1))
exists e1 x1 x2.(by(e1,x2) & n_machine(x2) & Actor(e1,x1) & v_stand(e1) & n_man(x1))