let X be RealBanachSpace; for x being sequence of X st X is Reflexive & ||.x.|| is bounded holds
ex x0 being sequence of X st
( x0 is subsequence of x & x0 is weakly-convergent )
let x be sequence of X; ( X is Reflexive & ||.x.|| is bounded implies ex x0 being sequence of X st
( x0 is subsequence of x & x0 is weakly-convergent ) )
assume that
A2:
X is Reflexive
and
A3:
||.x.|| is bounded
; ex x0 being sequence of X st
( x0 is subsequence of x & x0 is weakly-convergent )
set L = ClNLin (rng x);
reconsider L0 = the carrier of (ClNLin (rng x)) as Subset of X by DUALSP01:def 16;
LM1:
for z being object st z in rng x holds
z in the carrier of (ClNLin (rng x))
proof
let z be
object ;
( z in rng x implies z in the carrier of (ClNLin (rng x)) )
assume
z in rng x
;
z in the carrier of (ClNLin (rng x))
then C14:
z in Lin (rng x)
by RLVECT_3:15;
ex
Z being
Subset of
X st
(
Z = the
carrier of
(Lin (rng x)) &
ClNLin (rng x) = NORMSTR(#
(Cl Z),
(Zero_ ((Cl Z),X)),
(Add_ ((Cl Z),X)),
(Mult_ ((Cl Z),X)),
(Norm_ ((Cl Z),X)) #) )
by NORMSP_3:def 20;
hence
z in the
carrier of
(ClNLin (rng x))
by NORMSP_3:4, C14, TARSKI:def 3;
verum
end;
per cases
( rng x c= {(0. X)} or not rng x c= {(0. X)} )
;
suppose
not
rng x c= {(0. X)}
;
ex x0 being sequence of X st
( x0 is subsequence of x & x0 is weakly-convergent )then consider z being
object such that B11:
(
z in rng x & not
z in {(0. X)} )
;
B12:
(
z in rng x &
z <> 0. X )
by B11, TARSKI:def 1;
B17:
z in the
carrier of
(ClNLin (rng x))
by LM1, B11;
0. X = 0. (ClNLin (rng x))
by DUALSP01:def 16;
then A11:
not
ClNLin (rng x) is
trivial
by B12, B17;
A12:
ClNLin (rng x) is
Reflexive
by A2, NORMSP_4:29;
DualSp (DualSp (ClNLin (rng x))) is
separable
by A11, A12, NORMSP_4:25;
then A4:
DualSp (ClNLin (rng x)) is
separable
by Th73;
set F =
BidualFunc (ClNLin (rng x));
rng x c= the
carrier of
(ClNLin (rng x))
by LM1;
then reconsider x1 =
x as
sequence of
(ClNLin (rng x)) by FUNCT_2:6;
for
i being
Nat holds
||.x1.|| . i = ||.x.|| . i
then B13:
||.x1.|| = ||.x.||
;
then consider r being
Real such that A5:
for
n being
Nat holds
||.x1.|| . n < r
by A3, SEQ_2:def 3;
for
n being
Nat holds
||.((BidualFunc (ClNLin (rng x))) * x1).|| . n < r
then A6:
||.((BidualFunc (ClNLin (rng x))) * x1).|| is
bounded_above
;
consider s being
Real such that A7:
for
n being
Nat holds
s < ||.x1.|| . n
by B13, A3, SEQ_2:def 4;
for
n being
Nat holds
s < ||.((BidualFunc (ClNLin (rng x))) * x1).|| . n
then
||.((BidualFunc (ClNLin (rng x))) * x1).|| is
bounded_below
;
then consider f1 being
sequence of
(DualSp (DualSp (ClNLin (rng x)))) such that A9:
(
f1 is
subsequence of
(BidualFunc (ClNLin (rng x))) * x1 &
f1 is
weakly*-convergent )
by A4, A6, Th814;
consider L1 being
increasing sequence of
NAT such that A91:
f1 = ((BidualFunc (ClNLin (rng x))) * x1) * L1
by A9, VALUED_0:def 17;
reconsider x01 =
x1 * L1 as
sequence of
(ClNLin (rng x)) ;
f1 = (BidualFunc (ClNLin (rng x))) * x01
by A91, RELAT_1:36;
then HX:
x01 is
weakly-convergent
by A9, A12, Lm813A;
BX:
the
carrier of
(ClNLin (rng x)) c= the
carrier of
X
by DUALSP01:def 16;
then reconsider x0 =
x01 as
sequence of
X by FUNCT_2:7;
reconsider y =
w-lim x01 as
Point of
X by BX;
for
h being
Lipschitzian linear-Functional of
X holds
(
h * x0 is
convergent &
lim (h * x0) = h . y )
then
x0 is
weakly-convergent
;
hence
ex
x0 being
sequence of
X st
(
x0 is
subsequence of
x &
x0 is
weakly-convergent )
;
verum end; end;