let X, Y be Ideal of L; ( F c= X & ( for I being Ideal of L st F c= I holds
X c= I ) & F c= Y & ( for I being Ideal of L st F c= I holds
Y c= I ) implies X = Y )
assume
( F c= X & ( for I being Ideal of L st F c= I holds
X c= I ) & F c= Y & ( for I being Ideal of L st F c= I holds
Y c= I ) )
; X = Y
then
( X c= Y & Y c= X )
;
hence
X = Y
by XBOOLE_0:def 10; verum