let p be Real; ( 1 <= p implies the_set_of_RealSequences_l^ p is linearly-closed )
assume A1:
p >= 1
; the_set_of_RealSequences_l^ p is linearly-closed
set W = the_set_of_RealSequences_l^ p;
A2:
for v, u being VECTOR of Linear_Space_of_RealSequences st v in the_set_of_RealSequences_l^ p & u in the_set_of_RealSequences_l^ p holds
v + u in the_set_of_RealSequences_l^ p
proof
let v,
u be
VECTOR of
Linear_Space_of_RealSequences;
( v in the_set_of_RealSequences_l^ p & u in the_set_of_RealSequences_l^ p implies v + u in the_set_of_RealSequences_l^ p )
assume that A3:
v in the_set_of_RealSequences_l^ p
and A4:
u in the_set_of_RealSequences_l^ p
;
v + u in the_set_of_RealSequences_l^ p
A5:
(seq_id (v + u)) rto_power p is
summable
proof
v in the_set_of_RealSequences
by A1, A3, Def2;
then reconsider vq =
v as
Real_Sequence by RSSPACE:def 1;
set up =
(seq_id u) rto_power p;
set vp =
(seq_id v) rto_power p;
set p1 = 1
/ p;
A6:
(seq_id v) rto_power p = vq rto_power p
by RSSPACE:3;
(seq_id v) rto_power p is
summable
by A1, A3, Def2;
then
Partial_Sums ((seq_id v) rto_power p) is
bounded_above
by A7, SERIES_1:20;
then consider r being
real number such that A10:
for
n being
set st
n in dom (Partial_Sums ((seq_id v) rto_power p)) holds
(Partial_Sums ((seq_id v) rto_power p)) . n < r
by SEQ_2:def 1;
A11:
1
/ p > 0
by A1, XREAL_1:141;
reconsider r =
r as
Real by XREAL_0:def 1;
A12:
Partial_Sums ((seq_id v) rto_power p) is
V41()
by A7, SERIES_1:19;
then consider q being
Real such that A15:
for
n being
set st
n in dom (Partial_Sums ((seq_id v) rto_power p)) holds
((Partial_Sums ((seq_id v) rto_power p)) . n) to_power (1 / p) < q
;
u in the_set_of_RealSequences
by A1, A4, Def2;
then reconsider uq =
u as
Real_Sequence by RSSPACE:def 1;
A16:
seq_id u = uq
by RSSPACE:3;
A17:
(seq_id v) + (seq_id u) =
seq_id ((seq_id v) + (seq_id u))
by RSSPACE:3
.=
seq_id (v + u)
by RSSPACE:4, RSSPACE:def 7
;
(seq_id u) rto_power p is
summable
by A1, A4, Def2;
then
Partial_Sums ((seq_id u) rto_power p) is
bounded_above
by A7, SERIES_1:20;
then consider r1 being
real number such that A18:
for
n being
set st
n in dom (Partial_Sums ((seq_id u) rto_power p)) holds
(Partial_Sums ((seq_id u) rto_power p)) . n < r1
by SEQ_2:def 1;
reconsider r1 =
r1 as
Real by XREAL_0:def 1;
A19:
Partial_Sums ((seq_id u) rto_power p) is
V41()
by A7, SERIES_1:19;
then consider q1 being
Real such that A22:
for
n being
set st
n in dom (Partial_Sums ((seq_id u) rto_power p)) holds
((Partial_Sums ((seq_id u) rto_power p)) . n) to_power (1 / p) < q1
;
A23:
(seq_id u) rto_power p = uq rto_power p
by RSSPACE:3;
set g =
q + q1;
A24:
p * (1 / p) =
(p * 1) / p
by XCMPLX_1:75
.=
1
by A1, XCMPLX_1:60
;
now let n be
Element of
NAT ;
( ( for n being Element of NAT holds
( ( 0 < abs ((vq + uq) . n) or 0 = abs ((vq + uq) . n) ) & 0 <= ((vq + uq) rto_power p) . n ) ) & (Partial_Sums ((vq + uq) rto_power p)) . n < (q + q1) to_power p )
NAT = dom (Partial_Sums ((seq_id u) rto_power p))
by SEQ_1:4;
then A26:
((Partial_Sums ((seq_id u) rto_power p)) . n) to_power (1 / p) < q1
by A22;
NAT = dom (Partial_Sums ((seq_id v) rto_power p))
by SEQ_1:4;
then A27:
(((Partial_Sums ((seq_id u) rto_power p)) . n) to_power (1 / p)) + (((Partial_Sums ((seq_id v) rto_power p)) . n) to_power (1 / p)) < q + q1
by A15, A26, XREAL_1:10;
((Partial_Sums ((vq + uq) rto_power p)) . n) to_power (1 / p) <= (((Partial_Sums ((seq_id u) rto_power p)) . n) to_power (1 / p)) + (((Partial_Sums ((seq_id v) rto_power p)) . n) to_power (1 / p))
by A1, A6, A23, Th2;
then A28:
((Partial_Sums ((vq + uq) rto_power p)) . n) to_power (1 / p) < q + q1
by A27, XXREAL_0:2;
then A33:
0 <= ((vq + uq) rto_power p) . 0
;
A34:
(Partial_Sums ((vq + uq) rto_power p)) . 0 <= (Partial_Sums ((vq + uq) rto_power p)) . n
by A31, SEQM_3:21, SERIES_1:19;
then
0 <= (Partial_Sums ((vq + uq) rto_power p)) . n
by A33, SERIES_1:def 1;
then
((Partial_Sums ((vq + uq) rto_power p)) . n) to_power (1 / p) >= 0
by A11, Lm1;
hence
(Partial_Sums ((vq + uq) rto_power p)) . n < (q + q1) to_power p
by A1, A28, A25, A29, A34, A33, Th1, SERIES_1:def 1;
verum end;
then A35:
for
n being
Element of
NAT holds
(
Partial_Sums ((vq + uq) rto_power p) is
bounded_above &
0 <= ((vq + uq) rto_power p) . n )
by SEQ_2:def 3;
seq_id v = vq
by RSSPACE:3;
hence
(seq_id (v + u)) rto_power p is
summable
by A35, A16, A17, SERIES_1:20;
verum
end;
v + u =
(seq_id v) + (seq_id u)
by RSSPACE:4, RSSPACE:def 7
.=
seq_id ((seq_id v) + (seq_id u))
by RSSPACE:3
.=
seq_id (v + u)
by RSSPACE:4, RSSPACE:def 7
;
then reconsider w =
v + u as
Real_Sequence ;
reconsider w =
w as
set ;
w in the_set_of_RealSequences
by RSSPACE:def 1;
hence
v + u in the_set_of_RealSequences_l^ p
by A1, A5, Def2;
verum
end;
for a being Real
for v being VECTOR of Linear_Space_of_RealSequences st v in the_set_of_RealSequences_l^ p holds
a * v in the_set_of_RealSequences_l^ p
hence
the_set_of_RealSequences_l^ p is linearly-closed
by A2, RLSUB_1:def 1; verum