let p be Real; ( 1 <= p implies for lp being RealNormSpace st lp = NORMSTR(# (the_set_of_RealSequences_l^ p),(Zero_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(Add_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(Mult_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(l_norm^ p) #) holds
for vseq being sequence of lp st vseq is Cauchy_sequence_by_Norm holds
vseq is convergent )
assume A1:
1 <= p
; for lp being RealNormSpace st lp = NORMSTR(# (the_set_of_RealSequences_l^ p),(Zero_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(Add_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(Mult_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(l_norm^ p) #) holds
for vseq being sequence of lp st vseq is Cauchy_sequence_by_Norm holds
vseq is convergent
A2:
1 / p > 0
by A1, XREAL_1:139;
let lp be RealNormSpace; ( lp = NORMSTR(# (the_set_of_RealSequences_l^ p),(Zero_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(Add_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(Mult_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(l_norm^ p) #) implies for vseq being sequence of lp st vseq is Cauchy_sequence_by_Norm holds
vseq is convergent )
assume A3:
lp = NORMSTR(# (the_set_of_RealSequences_l^ p),(Zero_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(Add_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(Mult_ ((the_set_of_RealSequences_l^ p),Linear_Space_of_RealSequences)),(l_norm^ p) #)
; for vseq being sequence of lp st vseq is Cauchy_sequence_by_Norm holds
vseq is convergent
let vseq be sequence of lp; ( vseq is Cauchy_sequence_by_Norm implies vseq is convergent )
assume A4:
vseq is Cauchy_sequence_by_Norm
; vseq is convergent
defpred S1[ object , object ] means ex i being Nat st
( $1 = i & ex rseqi being Real_Sequence st
( ( for n being Nat holds rseqi . n = (seq_id (vseq . n)) . i ) & rseqi is convergent & $2 = lim rseqi ) );
A5: p * (1 / p) =
(p * 1) / p
by XCMPLX_1:74
.=
1
by A1, XCMPLX_1:60
;
A6:
for x being object st x in NAT holds
ex y being object st
( y in REAL & S1[x,y] )
proof
let x be
object ;
( x in NAT implies ex y being object st
( y in REAL & S1[x,y] ) )
assume
x in NAT
;
ex y being object st
( y in REAL & S1[x,y] )
then reconsider i =
x as
Nat ;
deffunc H1(
Nat)
-> Element of
REAL =
(seq_id (vseq . $1)) . i;
consider rseqi being
Real_Sequence such that A7:
for
n being
Nat holds
rseqi . n = H1(
n)
from SEQ_1:sch 1();
reconsider lr =
lim rseqi as
Element of
REAL by XREAL_0:def 1;
take
lr
;
( lr in REAL & S1[x,lr] )
now for e1 being Real st e1 > 0 holds
ex k being Nat st
for m being Nat st k <= m holds
|.((rseqi . m) - (rseqi . k)).| < e1let e1 be
Real;
( e1 > 0 implies ex k being Nat st
for m being Nat st k <= m holds
|.((rseqi . m) - (rseqi . k)).| < e1 )assume A8:
e1 > 0
;
ex k being Nat st
for m being Nat st k <= m holds
|.((rseqi . m) - (rseqi . k)).| < e1reconsider e =
e1 as
Real ;
thus
ex
k being
Nat st
for
m being
Nat st
k <= m holds
|.((rseqi . m) - (rseqi . k)).| < e1
verumproof
consider k being
Nat such that A9:
for
n,
m being
Nat st
n >= k &
m >= k holds
||.((vseq . n) - (vseq . m)).|| < e
by A4, A8, RSSPACE3:8;
for
m being
Nat st
k <= m holds
|.((rseqi . m) - (rseqi . k)).| < e
proof
let m be
Nat;
( k <= m implies |.((rseqi . m) - (rseqi . k)).| < e )
assume A10:
k <= m
;
|.((rseqi . m) - (rseqi . k)).| < e
A11:
||.((vseq . m) - (vseq . k)).|| = (Sum ((seq_id ((vseq . m) - (vseq . k))) rto_power p)) to_power (1 / p)
by A3, Def3;
then
(Sum ((seq_id ((vseq . m) - (vseq . k))) rto_power p)) to_power (1 / p) < e
by A9, A10;
then A12:
((Sum ((seq_id ((vseq . m) - (vseq . k))) rto_power p)) to_power (1 / p)) to_power p < e to_power p
by A1, A11, Th1, NORMSP_1:4;
reconsider vsem =
vseq . m,
vsek =
vseq . k as
VECTOR of
lp ;
A26:
for
a,
b,
c being
Real st
a >= 0 &
b > 0 &
c > 0 holds
(a to_power b) to_power c = a to_power (b * c)
((seq_id ((vseq . m) - (vseq . k))) rto_power p) . i = |.((seq_id ((vseq . m) - (vseq . k))) . i).| to_power p
by Def1;
then A30:
(((seq_id ((vseq . m) - (vseq . k))) rto_power p) . i) to_power (1 / p) =
|.((seq_id ((vseq . m) - (vseq . k))) . i).| to_power 1
by A1, A2, A5, A26, COMPLEX1:46
.=
|.((seq_id ((vseq . m) - (vseq . k))) . i).|
by POWER:25
;
A31:
rseqi . m = (seq_id (vseq . m)) . i
by A7;
A32:
(seq_id ((vseq . m) - (vseq . k))) rto_power p is
summable
by A1, A3, Th10;
then A33:
((seq_id ((vseq . m) - (vseq . k))) rto_power p) . i <= Sum ((seq_id ((vseq . m) - (vseq . k))) rto_power p)
by A13, RSSPACE2:3;
((Sum ((seq_id ((vseq . m) - (vseq . k))) rto_power p)) to_power (1 / p)) to_power p =
(Sum ((seq_id ((vseq . m) - (vseq . k))) rto_power p)) to_power ((1 / p) * p)
by A1, A2, A32, A13, HOLDER_1:2, SERIES_1:18
.=
Sum ((seq_id ((vseq . m) - (vseq . k))) rto_power p)
by A5, POWER:25
;
then A34:
((seq_id ((vseq . m) - (vseq . k))) rto_power p) . i < e to_power p
by A12, A33, XXREAL_0:2;
A35:
rseqi . k = (seq_id (vseq . k)) . i
by A7;
vsem - vsek = (seq_id vsem) - (seq_id vsek)
by A1, A3, Th10;
then A36:
|.((seq_id ((vseq . m) - (vseq . k))) . i).| =
|.(((seq_id (vseq . m)) . i) + ((- (seq_id (vseq . k))) . i)).|
by SEQ_1:7
.=
|.(((seq_id (vseq . m)) . i) + (- ((seq_id (vseq . k)) . i))).|
by SEQ_1:10
.=
|.((rseqi . m) - (rseqi . k)).|
by A31, A35
;
(e to_power p) to_power (1 / p) =
e to_power ((1 / p) * p)
by A8, POWER:33
.=
e to_power 1
by A1, XCMPLX_1:106
.=
e
by POWER:25
;
hence
|.((rseqi . m) - (rseqi . k)).| < e
by A2, A13, A30, A34, A36, Th1;
verum
end;
hence
ex
k being
Nat st
for
m being
Nat st
k <= m holds
|.((rseqi . m) - (rseqi . k)).| < e1
;
verum
end; end;
then
rseqi is
convergent
by SEQ_4:41;
hence
(
lr in REAL &
S1[
x,
lr] )
by A7;
verum
end;
consider f being sequence of REAL such that
A37:
for x being object st x in NAT holds
S1[x,f . x]
from FUNCT_2:sch 1(A6);
reconsider tseq = f as Real_Sequence ;
A40:
for e being Real st e > 0 holds
ex k being Nat st
for n being Nat st n >= k holds
( ((seq_id tseq) - (seq_id (vseq . n))) rto_power p is summable & Sum (((seq_id tseq) - (seq_id (vseq . n))) rto_power p) < e )
proof
A41:
for
n,
i being
Nat for
rseq being
Real_Sequence st ( for
m being
Nat holds
rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . i ) holds
(
rseq is
convergent &
lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . i )
proof
let n be
Nat;
for i being Nat
for rseq being Real_Sequence st ( for m being Nat holds rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . i ) holds
( rseq is convergent & lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . i )
defpred S2[
Nat]
means for
rseq being
Real_Sequence st ( for
m being
Nat holds
rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . $1 ) holds
(
rseq is
convergent &
lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . $1 );
A42:
for
m,
k being
Nat holds
seq_id ((vseq . m) - (vseq . k)) = (seq_id (vseq . m)) - (seq_id (vseq . k))
now for i being Nat st ( for rseq being Real_Sequence st ( for m being Nat holds rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . i ) holds
( rseq is convergent & lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . i ) ) holds
for rseq being Real_Sequence st ( for m being Nat holds rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . (i + 1) ) holds
( rseq is convergent & lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . (i + 1) )let i be
Nat;
( ( for rseq being Real_Sequence st ( for m being Nat holds rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . i ) holds
( rseq is convergent & lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . i ) ) implies for rseq being Real_Sequence st ( for m being Nat holds rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . (i + 1) ) holds
( rseq is convergent & lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . (i + 1) ) )assume A43:
for
rseq being
Real_Sequence st ( for
m being
Nat holds
rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . i ) holds
(
rseq is
convergent &
lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . i )
;
for rseq being Real_Sequence st ( for m being Nat holds rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . (i + 1) ) holds
( rseq is convergent & lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . (i + 1) )thus
for
rseq being
Real_Sequence st ( for
m being
Nat holds
rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . (i + 1) ) holds
(
rseq is
convergent &
lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . (i + 1) )
verumproof
deffunc H1(
Nat)
-> Element of
REAL =
(Partial_Sums ((seq_id ((vseq . $1) - (vseq . n))) rto_power p)) . i;
consider rseqb being
Real_Sequence such that A44:
for
m being
Nat holds
rseqb . m = H1(
m)
from SEQ_1:sch 1();
consider rseq0 being
Real_Sequence such that A45:
for
m being
Nat holds
rseq0 . m = (seq_id (vseq . m)) . (i + 1)
and A46:
rseq0 is
convergent
and A47:
tseq . (i + 1) = lim rseq0
by A38;
let rseq be
Real_Sequence;
( ( for m being Nat holds rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . (i + 1) ) implies ( rseq is convergent & lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . (i + 1) ) )
assume A48:
for
m being
Nat holds
rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . (i + 1)
;
( rseq is convergent & lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . (i + 1) )
A50:
lim rseqb = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . i
by A43, A44;
A51:
rseqb is
convergent
by A43, A44;
then lim rseq =
(|.((lim rseq0) - ((seq_id (vseq . n)) . (i + 1))).| to_power p) + (lim rseqb)
by A1, A46, A49, Lm9
.=
(|.((tseq . (i + 1)) + (- ((seq_id (vseq . n)) . (i + 1)))).| to_power p) + (lim rseqb)
by A47
.=
(|.((tseq . (i + 1)) + ((- (seq_id (vseq . n))) . (i + 1))).| to_power p) + (lim rseqb)
by SEQ_1:10
.=
(|.((tseq - (seq_id (vseq . n))) . (i + 1)).| to_power p) + (lim rseqb)
by SEQ_1:7
.=
(((tseq - (seq_id (vseq . n))) rto_power p) . (i + 1)) + ((Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . i)
by A50, Def1
.=
(Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . (i + 1)
by SERIES_1:def 1
;
hence
(
rseq is
convergent &
lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . (i + 1) )
by A1, A51, A46, A49, Lm9;
verum
end; end;
then A52:
for
i being
Nat st
S2[
i] holds
S2[
i + 1]
;
then A58:
S2[
0 ]
;
for
i being
Nat holds
S2[
i]
from NAT_1:sch 2(A58, A52);
hence
for
i being
Nat for
rseq being
Real_Sequence st ( for
m being
Nat holds
rseq . m = (Partial_Sums ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) . i ) holds
(
rseq is
convergent &
lim rseq = (Partial_Sums (((seq_id tseq) - (seq_id (vseq . n))) rto_power p)) . i )
;
verum
end;
let e2 be
Real;
( e2 > 0 implies ex k being Nat st
for n being Nat st n >= k holds
( ((seq_id tseq) - (seq_id (vseq . n))) rto_power p is summable & Sum (((seq_id tseq) - (seq_id (vseq . n))) rto_power p) < e2 ) )
assume A59:
e2 > 0
;
ex k being Nat st
for n being Nat st n >= k holds
( ((seq_id tseq) - (seq_id (vseq . n))) rto_power p is summable & Sum (((seq_id tseq) - (seq_id (vseq . n))) rto_power p) < e2 )
set e =
e2 / 2;
reconsider e1 =
(e2 / 2) to_power (1 / p) as
Real ;
e2 / 2
> 0
by A59, XREAL_1:215;
then
e1 > 0
by POWER:34;
then consider k being
Nat such that A60:
for
n,
m being
Nat st
n >= k &
m >= k holds
||.((vseq . n) - (vseq . m)).|| < e1
by A4, RSSPACE3:8;
A61:
for
m,
n being
Nat st
n >= k &
m >= k holds
(
(seq_id ((vseq . m) - (vseq . n))) rto_power p is
summable &
Sum ((seq_id ((vseq . m) - (vseq . n))) rto_power p) < e2 / 2 & ( for
i being
Nat holds
0 <= ((seq_id ((vseq . m) - (vseq . n))) rto_power p) . i ) )
proof
let m,
n be
Nat;
( n >= k & m >= k implies ( (seq_id ((vseq . m) - (vseq . n))) rto_power p is summable & Sum ((seq_id ((vseq . m) - (vseq . n))) rto_power p) < e2 / 2 & ( for i being Nat holds 0 <= ((seq_id ((vseq . m) - (vseq . n))) rto_power p) . i ) ) )
assume that A62:
n >= k
and A63:
m >= k
;
( (seq_id ((vseq . m) - (vseq . n))) rto_power p is summable & Sum ((seq_id ((vseq . m) - (vseq . n))) rto_power p) < e2 / 2 & ( for i being Nat holds 0 <= ((seq_id ((vseq . m) - (vseq . n))) rto_power p) . i ) )
||.((vseq . m) - (vseq . n)).|| < e1
by A60, A62, A63;
then
the
normF of
lp . ((vseq . m) - (vseq . n)) < e1
;
then A64:
(Sum ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) to_power (1 / p) < e1
by A3, Def3;
A65:
for
i being
Nat holds
((seq_id ((vseq . m) - (vseq . n))) rto_power p) . i >= 0
A66:
(seq_id ((vseq . m) - (vseq . n))) rto_power p is
summable
by A1, A3, Th10;
then A67:
(Sum ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) to_power (1 / p) >= 0
by A2, A65, Lm1, SERIES_1:18;
A68:
e1 to_power p =
(e2 / 2) to_power ((1 / p) * p)
by A59, POWER:33, XREAL_1:215
.=
(e2 / 2) to_power 1
by A1, XCMPLX_1:106
.=
e2 / 2
by POWER:25
;
((Sum ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) to_power (1 / p)) to_power p =
(Sum ((seq_id ((vseq . m) - (vseq . n))) rto_power p)) to_power ((1 / p) * p)
by A1, A2, A65, A66, HOLDER_1:2, SERIES_1:18
.=
Sum ((seq_id ((vseq . m) - (vseq . n))) rto_power p)
by A5, POWER:25
;
hence
(
(seq_id ((vseq . m) - (vseq . n))) rto_power p is
summable &
Sum ((seq_id ((vseq . m) - (vseq . n))) rto_power p) < e2 / 2 & ( for
i being
Nat holds
0 <= ((seq_id ((vseq . m) - (vseq . n))) rto_power p) . i ) )
by A1, A3, A65, A64, A68, A67, Th1, Th10;
verum
end;
A69:
e2 > e2 / 2
by A59, XREAL_1:216;
for
n being
Nat st
n >= k holds
(
((seq_id tseq) - (seq_id (vseq . n))) rto_power p is
summable &
Sum (((seq_id tseq) - (seq_id (vseq . n))) rto_power p) < e2 )
hence
ex
k being
Nat st
for
n being
Nat st
n >= k holds
(
((seq_id tseq) - (seq_id (vseq . n))) rto_power p is
summable &
Sum (((seq_id tseq) - (seq_id (vseq . n))) rto_power p) < e2 )
;
verum
end;
(seq_id tseq) rto_power p is summable
then reconsider tv = tseq as Point of lp by A1, A3, Th10;
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
proof
let e be
Real;
( e > 0 implies ex m being Nat st
for n being Nat st n >= m holds
||.((vseq . n) - tv).|| < e )
assume A86:
e > 0
;
ex m being Nat st
for n being Nat st n >= m holds
||.((vseq . n) - tv).|| < e
set e1 =
e to_power p;
consider m being
Nat such that A87:
for
n being
Nat st
n >= m holds
(
((seq_id tseq) - (seq_id (vseq . n))) rto_power p is
summable &
Sum (((seq_id tseq) - (seq_id (vseq . n))) rto_power p) < e to_power p )
by A40, A86, POWER:34;
now for n being Nat st n >= m holds
||.((vseq . n) - tv).|| < elet n be
Nat;
( n >= m implies ||.((vseq . n) - tv).|| < e )assume A88:
n >= m
;
||.((vseq . n) - tv).|| < eA89:
Sum (((seq_id tseq) - (seq_id (vseq . n))) rto_power p) < e to_power p
by A87, A88;
for
i being
Nat holds
(((seq_id tseq) - (seq_id (vseq . n))) rto_power p) . i >= 0
then A90:
Sum (((seq_id tseq) - (seq_id (vseq . n))) rto_power p) >= 0
by A87, A88, SERIES_1:18;
A91:
(e to_power p) to_power (1 / p) =
e to_power (p * (1 / p))
by A86, POWER:33
.=
e to_power 1
by A1, XCMPLX_1:106
.=
e
by POWER:25
;
(Sum (((seq_id tv) - (seq_id (vseq . n))) rto_power p)) to_power (1 / p) =
(Sum ((seq_id ((seq_id tv) - (seq_id (vseq . n)))) rto_power p)) to_power (1 / p)
.=
(Sum ((seq_id (tv - (vseq . n))) rto_power p)) to_power (1 / p)
by A1, A3, Th10
.=
||.(tv + (- (vseq . n))).||
by A3, Def3
.=
||.(- ((vseq . n) - tv)).||
by RLVECT_1:33
.=
||.((vseq . n) - tv).||
by NORMSP_1:2
;
hence
||.((vseq . n) - tv).|| < e
by A2, A90, A89, A91, Th1;
verum end;
hence
ex
m being
Nat st
for
n being
Nat st
n >= m holds
||.((vseq . n) - tv).|| < e
;
verum
end;
hence
vseq is convergent
by NORMSP_1:def 6; verum