A man working on metal with sparks flying.
The man is a welder.
Working on metal doesn't imply he is a welder.
exists e2 e1 x1 x2 x3 x4.(a_topic(x1) & Actor(e2,x4) & v_fly(e2) & with(e1,x4) & n_sparks(x4) & on(e1,x3) & n_metal(x3) & Actor(e1,x2) & v_work(e1) & (x1 = x2) & n_man(x1))
exists p1 x1.(n_man(x1) & exists x2.((x1 = x2) & n_welder(x2)))