A man does work on a stone part of a building.
A man works on some stones.
does work is another way of saying works on
exists e1 x1 x2 x3 x4.(on(e1,x2) & of(x2,x4) & n_building(x4) & n_part(x2) & of(x2,x3) & n_stone(x3) & Actor(e1,x1) & v_work(e1) & n_man(x1))
exists e1 x1 x2.(on(e1,x2) & n_stone(x2) & Actor(e1,x1) & v_work(e1) & n_man(x1))