A man works on a roof with a nail gun.
A man doesn't work on a roof
If a man doesn't work, then he cannot also work.
exists e1 x1 x2 x3 x4.(on(e1,x2) & with(x2,x3) & n_gun(x3) & of(x3,x4) & n_nail(x4) & n_roof(x2) & Actor(e1,x1) & v_work(e1) & n_man(x1))
exists x1.(-exists e1 x2.(on(e1,x2) & n_roof(x2) & Actor(e1,x1) & v_work(e1)) & n_man(x1))