Two doctors perform an operation.
The doctors are saving a life.
Just because the doctors are doing an operation, it doesn't mean they are saving a life.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_operation(x2) & n_doctor(x1) & card_eq_2(x1))
exists e1 x1 x2.(n_doctor(x1) & Theme(e1,x2) & Actor(e1,x1) & v_save(e1) & n_life(x2))