let C be non empty set ; for f, g being Membership_Func of C st g c= holds
g c=
let f, g be Membership_Func of C; ( g c= implies g c= )
assume A1:
for c being Element of C holds f . c <= g . c
; FUZZY_1:def 2 g c=
let c be Element of C; FUZZY_1:def 2 (max (f,(g \ f))) . c <= g . c
A2:
f . c <= g . c
by A1;
(max (f,(g \ f))) . c =
(min ((max (f,g)),(max (f,(1_minus f))))) . c
by FUZZY_1:9
.=
min (((max (f,g)) . c),((max (f,(1_minus f))) . c))
by FUZZY_1:5
.=
min ((max ((f . c),(g . c))),((max (f,(1_minus f))) . c))
by FUZZY_1:5
.=
min ((g . c),((max (f,(1_minus f))) . c))
by A2, XXREAL_0:def 10
;
hence
(max (f,(g \ f))) . c <= g . c
by XXREAL_0:17; verum