Man works on top of scaffolding.
Man is working.
Man working in common in both sentences
exists e1 x1 x2 x3.(on(e1,x2) & of(x2,x3) & n_scaffolding(x3) & n_top(x2) & Actor(e1,x1) & v_work(e1) & n_man(x1))
exists e1 x1.(Actor(e1,x1) & v_work(e1) & n_man(x1))