A man is carrying a mechanical device on a street.
A man is carrying a vacuum on a street.
Not all mechanical devices are a vacuum.
exists e1 s1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_carry(e1) & on(x2,x3) & n_street(x3) & n_device(x2) & a_mechanical(s1) & Theme(s1,x2) & n_man(x1))
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_carry(e1) & on(x2,x3) & n_street(x3) & n_vacuum(x2) & n_man(x1))