A man is sitting on the ground welding something.
A man is welding at work.
The man does not have to be at work to weld.
exists e1 e2 x1 x2 x3 x4.(n_ground(x2) & on(e1,x2) & Theme(e2,x4) & Actor(e2,x3) & v_weld(e2) & n_thing(x4) & (x2 = x3) & Actor(e1,x1) & v_sit(e1) & n_man(x1))
exists e1 x1 x2.(at(e1,x2) & n_work(x2) & Actor(e1,x1) & v_weld(e1) & n_man(x1))