let X be non empty set ; :: thesis: for f being with_the_same_dom Functional_Sequence of X,COMPLEX st ( for x being Element of X st x in dom (f . 0 ) holds
f # x is convergent ) holds
( lim (Re f) = Re (lim f) & lim (Im f) = Im (lim f) )
let f be with_the_same_dom Functional_Sequence of X,COMPLEX ; :: thesis: ( ( for x being Element of X st x in dom (f . 0 ) holds
f # x is convergent ) implies ( lim (Re f) = Re (lim f) & lim (Im f) = Im (lim f) ) )
assume A2:
for x being Element of X st x in dom (f . 0 ) holds
f # x is convergent
; :: thesis: ( lim (Re f) = Re (lim f) & lim (Im f) = Im (lim f) )
dom (lim (Re f)) = dom ((Re f) . 0 )
by MESFUNC8:def 10;
then P1:
dom (lim (Re f)) = dom (f . 0 )
by Def13;
P2:
dom (Re (lim f)) = dom (lim f)
by MESFUN6C:def 1;
then B1:
dom (lim (Re f)) = dom (Re (lim f))
by P1, Def12;
dom (lim (Im f)) = dom ((Im f) . 0 )
by MESFUNC8:def 10;
then Q1:
dom (lim (Im f)) = dom (f . 0 )
by Def14;
Q2:
dom (Im (lim f)) = dom (lim f)
by MESFUN6C:def 2;
then B2:
dom (lim (Im f)) = dom (Im (lim f))
by Q1, Def12;
P00:
now let x be
Element of
X;
:: thesis: ( x in dom (lim (Re f)) implies (lim (Re f)) . x = (Re (lim f)) . x )assume P01:
x in dom (lim (Re f))
;
:: thesis: (lim (Re f)) . x = (Re (lim f)) . xthen C1:
f # x is
convergent
by A2, P1;
then
Re (f # x) is
convergent
;
then PP:
(Re f) # x is
convergent
by P01, P1, Th7a;
(lim (Re f)) . x =
lim (R_EAL ((Re f) # x))
by P01, Def10a
.=
lim ((Re f) # x)
by PP, RINFSUP2:14
;
then
(lim (Re f)) . x = lim (Re (f # x))
by P01, P1, Th7a;
then P03:
(lim (Re f)) . x = Re (lim (f # x))
by C1, COMSEQ_3:41;
(Re (lim f)) . x = Re ((lim f) . x)
by P01, B1, MESFUN6C:def 1;
hence
(lim (Re f)) . x = (Re (lim f)) . x
by P03, P01, B1, P2, Def12;
:: thesis: verum end;
Re (lim f) is PartFunc of X,ExtREAL
by NUMBERS:31, RELSET_1:17;
hence
lim (Re f) = Re (lim f)
by B1, P00, PARTFUN1:34; :: thesis: lim (Im f) = Im (lim f)
P00:
now let x be
Element of
X;
:: thesis: ( x in dom (lim (Im f)) implies (lim (Im f)) . x = (Im (lim f)) . x )assume P01:
x in dom (lim (Im f))
;
:: thesis: (lim (Im f)) . x = (Im (lim f)) . xthen D1:
f # x is
convergent
by A2, Q1;
then
Im (f # x) is
convergent
;
then PP:
(Im f) # x is
convergent
by P01, Q1, Th7a;
(lim (Im f)) . x =
lim (R_EAL ((Im f) # x))
by P01, Def10a
.=
lim ((Im f) # x)
by PP, RINFSUP2:14
;
then
(lim (Im f)) . x = lim (Im (f # x))
by P01, Q1, Th7a;
then P03:
(lim (Im f)) . x = Im (lim (f # x))
by D1, COMSEQ_3:41;
(Im (lim f)) . x = Im ((lim f) . x)
by P01, B2, MESFUN6C:def 2;
hence
(lim (Im f)) . x = (Im (lim f)) . x
by P03, P01, B2, Q2, Def12;
:: thesis: verum end;
Im (lim f) is PartFunc of X,ExtREAL
by NUMBERS:31, RELSET_1:17;
hence
lim (Im f) = Im (lim f)
by B2, P00, PARTFUN1:34; :: thesis: verum