let f, g be Fuzzy_Negation; max (f,g) = (maxfuncreal [.0,1.]) . (f,g)
set A = [.0,1.];
set fg = max (f,g);
set mfg = (maxfuncreal [.0,1.]) . (f,g);
B1:
dom (max (f,g)) = [.0,1.]
by FUNCT_2:def 1;
AC:
( f in Funcs ([.0,1.],REAL) & g in Funcs ([.0,1.],REAL) & Funcs ([.0,1.],REAL) <> {} )
by LemmaFunc2;
(maxfuncreal [.0,1.]) . (f,g) in Funcs ([.0,1.],REAL)
by AC, BINOP_1:17;
then consider f1 being Function such that
C1:
( (maxfuncreal [.0,1.]) . (f,g) = f1 & dom f1 = [.0,1.] & rng f1 c= REAL )
by FUNCT_2:def 2;
for x being object st x in [.0,1.] holds
(max (f,g)) . x = ((maxfuncreal [.0,1.]) . (f,g)) . x
proof
let x be
object ;
( x in [.0,1.] implies (max (f,g)) . x = ((maxfuncreal [.0,1.]) . (f,g)) . x )
assume D0:
x in [.0,1.]
;
(max (f,g)) . x = ((maxfuncreal [.0,1.]) . (f,g)) . x
consider f2,
g2 being
Function of
[.0,1.],
REAL such that D1:
(
f2 = f &
g2 = g &
max (
f,
g)
= max (
f2,
g2) )
by MaxFuz;
(
dom f = [.0,1.] &
rng f c= REAL &
dom g = [.0,1.] &
rng g c= REAL )
by FUNCT_2:def 1, RELAT_1:def 19;
then reconsider fA =
f,
gA =
g as
Element of
Funcs (
[.0,1.],
REAL)
by FUNCT_2:def 2;
dom (maxreal .: (fA,gA)) = [.0,1.]
by FUNCT_2:def 1;
then (maxreal .: (fA,gA)) . x =
maxreal . (
(fA . x),
(gA . x))
by D0, FUNCOP_1:22
.=
max (
(fA . x),
(gA . x))
by REAL_LAT:def 2
.=
(max (f,g)) . x
by D1, D0, COUSIN2:def 2
;
hence
(max (f,g)) . x = ((maxfuncreal [.0,1.]) . (f,g)) . x
by REAL_LAT:def 4;
verum
end;
hence
max (f,g) = (maxfuncreal [.0,1.]) . (f,g)
by C1, B1, FUNCT_1:2; verum