let X be non empty set ; for Y being ComplexNormSpace st Y is complete holds
for seq being sequence of (C_NormSpace_of_BoundedFunctions (X,Y)) st seq is Cauchy_sequence_by_Norm holds
seq is convergent
let Y be ComplexNormSpace; ( Y is complete implies for seq being sequence of (C_NormSpace_of_BoundedFunctions (X,Y)) st seq is Cauchy_sequence_by_Norm holds
seq is convergent )
assume A1:
Y is complete
; for seq being sequence of (C_NormSpace_of_BoundedFunctions (X,Y)) st seq is Cauchy_sequence_by_Norm holds
seq is convergent
let vseq be sequence of (C_NormSpace_of_BoundedFunctions (X,Y)); ( vseq is Cauchy_sequence_by_Norm implies vseq is convergent )
assume A2:
vseq is Cauchy_sequence_by_Norm
; vseq is convergent
defpred S1[ set , set ] means ex xseq being sequence of Y st
( ( for n being Nat holds xseq . n = (modetrans ((vseq . n),X,Y)) . $1 ) & xseq is convergent & $2 = lim xseq );
A3:
for x being Element of X ex y being Element of Y st S1[x,y]
proof
let x be
Element of
X;
ex y being Element of Y st S1[x,y]
deffunc H1(
Nat)
-> Element of the
carrier of
Y =
(modetrans ((vseq . $1),X,Y)) . x;
consider xseq being
sequence of
Y such that A4:
for
n being
Element of
NAT holds
xseq . n = H1(
n)
from FUNCT_2:sch 4();
A5:
for
n being
Nat holds
xseq . n = H1(
n)
take
lim xseq
;
S1[x, lim xseq]
A6:
for
m,
k being
Nat holds
||.((xseq . m) - (xseq . k)).|| <= ||.((vseq . m) - (vseq . k)).||
proof
let m,
k be
Nat;
||.((xseq . m) - (xseq . k)).|| <= ||.((vseq . m) - (vseq . k)).||
A7:
(
k in NAT &
m in NAT )
by ORDINAL1:def 12;
vseq . k is
bounded Function of
X, the
carrier of
Y
by Def5;
then A8:
modetrans (
(vseq . k),
X,
Y)
= vseq . k
by Th14;
reconsider h1 =
(vseq . m) - (vseq . k) as
bounded Function of
X, the
carrier of
Y by Def5;
vseq . m is
bounded Function of
X, the
carrier of
Y
by Def5;
then A9:
modetrans (
(vseq . m),
X,
Y)
= vseq . m
by Th14;
(
xseq . m = (modetrans ((vseq . m),X,Y)) . x &
xseq . k = (modetrans ((vseq . k),X,Y)) . x )
by A4, A7;
then
(xseq . m) - (xseq . k) = h1 . x
by A9, A8, Th25;
hence
||.((xseq . m) - (xseq . k)).|| <= ||.((vseq . m) - (vseq . k)).||
by Th17;
verum
end;
now for e being Real st e > 0 holds
ex k being Nat st
for n, m being Nat st n >= k & m >= k holds
||.((xseq . n) - (xseq . m)).|| < elet e be
Real;
( e > 0 implies ex k being Nat st
for n, m being Nat st n >= k & m >= k holds
||.((xseq . n) - (xseq . m)).|| < e )assume A10:
e > 0
;
ex k being Nat st
for n, m being Nat st n >= k & m >= k holds
||.((xseq . n) - (xseq . m)).|| < ethus
ex
k being
Nat st
for
n,
m being
Nat st
n >= k &
m >= k holds
||.((xseq . n) - (xseq . m)).|| < e
verum end;
then
xseq is
Cauchy_sequence_by_Norm
by CSSPACE3:8;
then
xseq is
convergent
by A1;
hence
S1[
x,
lim xseq]
by A5;
verum
end;
consider f being Function of X, the carrier of Y such that
A13:
for x being Element of X holds S1[x,f . x]
from FUNCT_2:sch 3(A3);
reconsider tseq = f as Function of X, the carrier of Y ;
then A17:
||.vseq.|| is convergent
by SEQ_4:41;
A18:
tseq is bounded
A24:
for e being Real st e > 0 holds
ex k being Nat st
for n being Nat st n >= k holds
for x being Element of X holds ||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= e
proof
let e be
Real;
( e > 0 implies ex k being Nat st
for n being Nat st n >= k holds
for x being Element of X holds ||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= e )
assume
e > 0
;
ex k being Nat st
for n being Nat st n >= k holds
for x being Element of X holds ||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= e
then consider k being
Nat such that A25:
for
n,
m being
Nat st
n >= k &
m >= k holds
||.((vseq . n) - (vseq . m)).|| < e
by A2, CSSPACE3:8;
take
k
;
for n being Nat st n >= k holds
for x being Element of X holds ||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= e
now for n being Nat st n >= k holds
for x being Element of X holds ||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= elet n be
Nat;
( n >= k implies for x being Element of X holds ||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= e )assume A26:
n >= k
;
for x being Element of X holds ||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= enow for x being Element of X holds ||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= elet x be
Element of
X;
||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= econsider xseq being
sequence of
Y such that A27:
for
n being
Nat holds
xseq . n = (modetrans ((vseq . n),X,Y)) . x
and A28:
(
xseq is
convergent &
tseq . x = lim xseq )
by A13;
A29:
for
m,
k being
Nat holds
||.((xseq . m) - (xseq . k)).|| <= ||.((vseq . m) - (vseq . k)).||
proof
let m,
k be
Nat;
||.((xseq . m) - (xseq . k)).|| <= ||.((vseq . m) - (vseq . k)).||
vseq . k is
bounded Function of
X, the
carrier of
Y
by Def5;
then A30:
modetrans (
(vseq . k),
X,
Y)
= vseq . k
by Th14;
reconsider h1 =
(vseq . m) - (vseq . k) as
bounded Function of
X, the
carrier of
Y by Def5;
vseq . m is
bounded Function of
X, the
carrier of
Y
by Def5;
then A31:
modetrans (
(vseq . m),
X,
Y)
= vseq . m
by Th14;
(
xseq . m = (modetrans ((vseq . m),X,Y)) . x &
xseq . k = (modetrans ((vseq . k),X,Y)) . x )
by A27;
then
(xseq . m) - (xseq . k) = h1 . x
by A31, A30, Th25;
hence
||.((xseq . m) - (xseq . k)).|| <= ||.((vseq . m) - (vseq . k)).||
by Th17;
verum
end; A32:
for
m being
Nat st
m >= k holds
||.((xseq . n) - (xseq . m)).|| <= e
||.((xseq . n) - (tseq . x)).|| <= e
hence
||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= e
by A27;
verum end; hence
for
x being
Element of
X holds
||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= e
;
verum end;
hence
for
n being
Nat st
n >= k holds
for
x being
Element of
X holds
||.(((modetrans ((vseq . n),X,Y)) . x) - (tseq . x)).|| <= e
;
verum
end;
reconsider tseq = tseq as bounded Function of X, the carrier of Y by A18;
reconsider tv = tseq as Point of (C_NormSpace_of_BoundedFunctions (X,Y)) by Def5;
A39:
for e being Real st e > 0 holds
ex k being Nat st
for n being Nat st n >= k holds
||.((vseq . n) - tv).|| <= e
for e being Real st e > 0 holds
ex m being Nat st
for n being Nat st n >= m holds
||.((vseq . n) - tv).|| < e
hence
vseq is convergent
by CLVECT_1:def 15; verum