A man is singing into a microphone.
A man performs a song.
Not all men who are singing are performing a song.
exists e1 x1 x2.(into(e1,x2) & n_microphone(x2) & Actor(e1,x1) & v_sing(e1) & n_man(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_song(x2) & n_man(x1))