equation icon  1( p' p' ) ' (f;a) (f;b) --> -- ga \~/ p'\ ~/ b + gb \~/ a\ ~/ p' f(x)f(x ), 2( ) f (f;ab) --> 1-\ ~/ a\ ~/ b + gap'gbq' \~/ p' \~/ q' f(x)f(x'). 2