set X = dom (f1 (#) f2);
dom (f1 (#) f2) c= (dom f1) /\ (dom f2)
by VALUED_1:def 4;
then X:
( dom (f1 (#) f2) c= dom f1 & dom (f1 (#) f2) c= dom f2 )
by XBOOLE_1:18;
HA:
( f1 | (dom (f1 (#) f2)) is continuous & f2 | (dom (f1 (#) f2)) is continuous )
;
now let s1 be
Real_Sequence;
:: thesis: ( rng s1 c= dom (f1 (#) f2) & s1 is convergent & lim s1 in dom (f1 (#) f2) implies ( (f1 (#) f2) /* s1 is convergent & (f1 (#) f2) . (lim s1) = lim ((f1 (#) f2) /* s1) ) )assume A8:
(
rng s1 c= dom (f1 (#) f2) &
s1 is
convergent &
lim s1 in dom (f1 (#) f2) )
;
:: thesis: ( (f1 (#) f2) /* s1 is convergent & (f1 (#) f2) . (lim s1) = lim ((f1 (#) f2) /* s1) )then A9:
rng s1 c= (dom f1) /\ (dom f2)
by VALUED_1:def 4;
A10:
(
f1 /* s1 is
convergent &
f1 . (lim s1) = lim (f1 /* s1) )
by A8, Th14, X, HA;
A11:
(
f2 /* s1 is
convergent &
f2 . (lim s1) = lim (f2 /* s1) )
by A8, Th14, X, HA;
then A12:
(f1 /* s1) (#) (f2 /* s1) is
convergent
by A10, SEQ_2:28;
(f1 (#) f2) . (lim s1) =
(lim (f1 /* s1)) * (lim (f2 /* s1))
by A8, A10, A11, VALUED_1:def 4
.=
lim ((f1 /* s1) (#) (f2 /* s1))
by A10, A11, SEQ_2:29
.=
lim ((f1 (#) f2) /* s1)
by A9, RFUNCT_2:23
;
hence
(
(f1 (#) f2) /* s1 is
convergent &
(f1 (#) f2) . (lim s1) = lim ((f1 (#) f2) /* s1) )
by A9, A12, RFUNCT_2:23;
:: thesis: verum end;
then
(f1 (#) f2) | (dom (f1 (#) f2)) is continuous
by Th14;
hence
for b1 being PartFunc of REAL ,REAL st b1 = f1 (#) f2 holds
b1 is continuous
by RELAT_1:98; :: thesis: verum