set X = dom (f1 (#) f2);
dom (f1 (#) f2) c= (dom f1) /\ (dom f2)
by VALUED_1:def 4;
then A17:
( dom (f1 (#) f2) c= dom f1 & dom (f1 (#) f2) c= dom f2 )
by XBOOLE_1:18;
A18:
( f1 | (dom (f1 (#) f2)) is continuous & f2 | (dom (f1 (#) f2)) is continuous )
;
now let s1 be
Real_Sequence;
( 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 that A19:
rng s1 c= dom (f1 (#) f2)
and A20:
s1 is
convergent
and A21:
lim s1 in dom (f1 (#) f2)
;
( (f1 (#) f2) /* s1 is convergent & (f1 (#) f2) . (lim s1) = lim ((f1 (#) f2) /* s1) )A22:
(
f1 /* s1 is
convergent &
f2 /* s1 is
convergent )
by A17, A18, A19, A20, A21, Th14;
then A23:
(f1 /* s1) (#) (f2 /* s1) is
convergent
by SEQ_2:14;
A24:
rng s1 c= (dom f1) /\ (dom f2)
by A19, VALUED_1:def 4;
(
f1 . (lim s1) = lim (f1 /* s1) &
f2 . (lim s1) = lim (f2 /* s1) )
by A17, A18, A19, A20, A21, Th14;
then (f1 (#) f2) . (lim s1) =
(lim (f1 /* s1)) * (lim (f2 /* s1))
by A21, VALUED_1:def 4
.=
lim ((f1 /* s1) (#) (f2 /* s1))
by A22, SEQ_2:15
.=
lim ((f1 (#) f2) /* s1)
by A24, RFUNCT_2:8
;
hence
(
(f1 (#) f2) /* s1 is
convergent &
(f1 (#) f2) . (lim s1) = lim ((f1 (#) f2) /* s1) )
by A24, A23, RFUNCT_2:8;
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_1:69; verum