let X be RealBanachSpace; for Y being RealNormSpace
for vseq being sequence of (R_NormSpace_of_BoundedLinearOperators X,Y)
for tseq being Function of X,Y st ( for x being Point of X holds
( vseq # x is convergent & tseq . x = lim (vseq # x) ) ) holds
( tseq is bounded LinearOperator of X,Y & ( for x being Point of X holds ||.(tseq . x).|| <= (lim_inf ||.vseq.||) * ||.x.|| ) & ( for ttseq being Point of (R_NormSpace_of_BoundedLinearOperators X,Y) st ttseq = tseq holds
||.ttseq.|| <= lim_inf ||.vseq.|| ) )
let Y be RealNormSpace; for vseq being sequence of (R_NormSpace_of_BoundedLinearOperators X,Y)
for tseq being Function of X,Y st ( for x being Point of X holds
( vseq # x is convergent & tseq . x = lim (vseq # x) ) ) holds
( tseq is bounded LinearOperator of X,Y & ( for x being Point of X holds ||.(tseq . x).|| <= (lim_inf ||.vseq.||) * ||.x.|| ) & ( for ttseq being Point of (R_NormSpace_of_BoundedLinearOperators X,Y) st ttseq = tseq holds
||.ttseq.|| <= lim_inf ||.vseq.|| ) )
let vseq be sequence of (R_NormSpace_of_BoundedLinearOperators X,Y); for tseq being Function of X,Y st ( for x being Point of X holds
( vseq # x is convergent & tseq . x = lim (vseq # x) ) ) holds
( tseq is bounded LinearOperator of X,Y & ( for x being Point of X holds ||.(tseq . x).|| <= (lim_inf ||.vseq.||) * ||.x.|| ) & ( for ttseq being Point of (R_NormSpace_of_BoundedLinearOperators X,Y) st ttseq = tseq holds
||.ttseq.|| <= lim_inf ||.vseq.|| ) )
let tseq be Function of X,Y; ( ( for x being Point of X holds
( vseq # x is convergent & tseq . x = lim (vseq # x) ) ) implies ( tseq is bounded LinearOperator of X,Y & ( for x being Point of X holds ||.(tseq . x).|| <= (lim_inf ||.vseq.||) * ||.x.|| ) & ( for ttseq being Point of (R_NormSpace_of_BoundedLinearOperators X,Y) st ttseq = tseq holds
||.ttseq.|| <= lim_inf ||.vseq.|| ) ) )
set T = rng vseq;
set RNS = R_NormSpace_of_BoundedLinearOperators X,Y;
assume A1:
for x being Point of X holds
( vseq # x is convergent & tseq . x = lim (vseq # x) )
; ( tseq is bounded LinearOperator of X,Y & ( for x being Point of X holds ||.(tseq . x).|| <= (lim_inf ||.vseq.||) * ||.x.|| ) & ( for ttseq being Point of (R_NormSpace_of_BoundedLinearOperators X,Y) st ttseq = tseq holds
||.ttseq.|| <= lim_inf ||.vseq.|| ) )
A2:
for x, y being Point of X holds tseq . (x + y) = (tseq . x) + (tseq . y)
A7:
for x being Point of X ex K being real number st
( 0 <= K & ( for f being Point of (R_NormSpace_of_BoundedLinearOperators X,Y) st f in rng vseq holds
||.(f . x).|| <= K ) )
vseq in Funcs NAT ,the carrier of (R_NormSpace_of_BoundedLinearOperators X,Y)
by FUNCT_2:11;
then
ex f0 being Function st
( vseq = f0 & dom f0 = NAT & rng f0 c= the carrier of (R_NormSpace_of_BoundedLinearOperators X,Y) )
by FUNCT_2:def 2;
then consider L being real number such that
A12:
0 <= L
and
A13:
for f being Point of (R_NormSpace_of_BoundedLinearOperators X,Y) st f in rng vseq holds
||.f.|| <= L
by A7, Th5;
A14:
L + 0 < 1 + L
by XREAL_1:10;
for n being Element of NAT holds abs (||.vseq.|| . n) < 1 + L
then A16:
||.vseq.|| is bounded
by A12, SEQ_2:15;
A17:
for x being Point of X holds ||.(tseq . x).|| <= (lim_inf ||.vseq.||) * ||.x.||
proof
let x be
Point of
X;
||.(tseq . x).|| <= (lim_inf ||.vseq.||) * ||.x.||
A18:
||.x.|| (#) ||.vseq.|| is
bounded
by A16, SEQM_3:70;
A19:
for
n being
Element of
NAT holds
||.((vseq # x) . n).|| <= ||.(vseq . n).|| * ||.x.||
A20:
for
n being
Element of
NAT holds
||.(vseq # x).|| . n <= (||.x.|| (#) ||.vseq.||) . n
A22:
lim_inf (||.x.|| (#) ||.vseq.||) = (lim_inf ||.vseq.||) * ||.x.||
by A16, Th1, NORMSP_1:8;
A23:
(
vseq # x is
convergent &
tseq . x = lim (vseq # x) )
by A1;
then
||.(vseq # x).|| is
convergent
by LOPBAN_1:24;
then A24:
lim ||.(vseq # x).|| = lim_inf ||.(vseq # x).||
by RINFSUP1:91;
||.(vseq # x).|| is
bounded
by A23, LOPBAN_1:24, SEQ_2:27;
then
lim_inf ||.(vseq # x).|| <= lim_inf (||.x.|| (#) ||.vseq.||)
by A18, A20, RINFSUP1:93;
hence
||.(tseq . x).|| <= (lim_inf ||.vseq.||) * ||.x.||
by A23, A22, A24, LOPBAN_1:24;
verum
end;
then A26:
0 <= lim_inf ||.vseq.||
by A16, RINFSUP1:84;
A27:
for x being Point of X
for r being Element of REAL holds tseq . (r * x) = r * (tseq . x)
then reconsider tseq1 = tseq as bounded LinearOperator of X,Y by A2, A17, A26, LOPBAN_1:def 5, LOPBAN_1:def 6, LOPBAN_1:def 9;
for ttseq being Point of (R_NormSpace_of_BoundedLinearOperators X,Y) st ttseq = tseq holds
||.ttseq.|| <= lim_inf ||.vseq.||
hence
( tseq is bounded LinearOperator of X,Y & ( for x being Point of X holds ||.(tseq . x).|| <= (lim_inf ||.vseq.||) * ||.x.|| ) & ( for ttseq being Point of (R_NormSpace_of_BoundedLinearOperators X,Y) st ttseq = tseq holds
||.ttseq.|| <= lim_inf ||.vseq.|| ) )
by A2, A27, A17, A26, LOPBAN_1:def 5, LOPBAN_1:def 6, LOPBAN_1:def 9; verum