let G be RealNormSpace-Sequence; ( product G is reflexive & product G is discerning & product G is RealNormSpace-like )
A1:
product G = NORMSTR(# (product (carr G)),(zeros G),[:(addop G):],[:(multop G):],(productnorm G) #)
by Th6;
A2:
len G = len (carr G)
by PRVECT_1:def 11;
reconsider n = len G as Element of NAT ;
thus
product G is reflexive
( product G is discerning & product G is RealNormSpace-like )proof
reconsider z =
0. (product G) as
Element of
product (carr G) by A1;
A3:
for
i being
Element of
dom (carr G) holds
(normsequence (G,z)) . i = 0
for
i being
Element of
NAT st
i in dom (sqr (normsequence (G,z))) holds
(sqr (normsequence (G,z))) . i = 0
proof
let i be
Element of
NAT ;
( i in dom (sqr (normsequence (G,z))) implies (sqr (normsequence (G,z))) . i = 0 )
assume A4:
i in dom (sqr (normsequence (G,z)))
;
(sqr (normsequence (G,z))) . i = 0
len (normsequence (G,z)) = len G
by Def11;
then A5:
dom (normsequence (G,z)) = dom G
by FINSEQ_3:29;
dom (carr G) = dom G
by A2, FINSEQ_3:29;
then
dom (sqr (normsequence (G,z))) = dom (carr G)
by A5, VALUED_1:11;
then
((normsequence (G,z)) . i) ^2 = 0 ^2
by A3, A4;
hence
(sqr (normsequence (G,z))) . i = 0
by VALUED_1:11;
verum
end;
then
|.(normsequence (G,z)).| = 0
by Th3, SQUARE_1:17;
hence
||.(0. (product G)).|| = 0
by Th7;
NORMSP_0:def 6 verum
end;
thus
product G is discerning
product G is RealNormSpace-like
let x, y be Point of (product G); NORMSP_1:def 1 for b1 being object holds
( ||.(b1 * x).|| = |.b1.| * ||.x.|| & ||.(x + y).|| <= ||.x.|| + ||.y.|| )
let a be Real; ( ||.(a * x).|| = |.a.| * ||.x.|| & ||.(x + y).|| <= ||.x.|| + ||.y.|| )
reconsider z = x as Element of product (carr G) by A1;
reconsider xx = x, yy = y as Element of product (carr G) by A1;
reconsider ax = a * x as Element of product (carr G) by A1;
A7:
( ||.y.|| = |.(normsequence (G,yy)).| & |.((normsequence (G,xx)) + (normsequence (G,yy))).| <= |.(normsequence (G,xx)).| + |.(normsequence (G,yy)).| )
by Th7, EUCLID:12;
A8:
len (normsequence (G,ax)) = n
by CARD_1:def 7;
then A9:
dom (normsequence (G,ax)) = Seg n
by FINSEQ_1:def 3;
A10:
for i being Nat st i in dom (normsequence (G,ax)) holds
(normsequence (G,ax)) . i = (|.a.| * (normsequence (G,z))) . i
proof
let i be
Nat;
( i in dom (normsequence (G,ax)) implies (normsequence (G,ax)) . i = (|.a.| * (normsequence (G,z))) . i )
assume
i in dom (normsequence (G,ax))
;
(normsequence (G,ax)) . i = (|.a.| * (normsequence (G,z))) . i
then reconsider i0 =
i as
Element of
dom G by A9, FINSEQ_1:def 3;
reconsider i1 =
i0 as
Element of
dom (carr G) by A2, FINSEQ_3:29;
(
(carr G) . i0 = the
carrier of
(G . i0) &
dom (carr G) = dom G )
by A2, PRVECT_1:def 11, FINSEQ_3:29;
then reconsider axi0 =
ax . i0,
zi0 =
z . i0 as
Element of
(G . i0) by CARD_3:9;
reconsider aa =
a as
Element of
REAL by XREAL_0:def 1;
([:(multop G):] . (aa,z)) . i1 = ((multop G) . i1) . (
a,
zi0)
by Def2;
then
axi0 = a * zi0
by A1, Def8;
then
||.axi0.|| = |.a.| * ||.zi0.||
by NORMSP_1:def 1;
then
||.axi0.|| = |.a.| * ((normsequence (G,z)) . i0)
by Def11;
then
||.axi0.|| = (|.a.| * (normsequence (G,z))) . i0
by RVSUM_1:44;
hence
(normsequence (G,ax)) . i = (|.a.| * (normsequence (G,z))) . i
by Def11;
verum
end;
len (|.a.| * (normsequence (G,z))) = n
by CARD_1:def 7;
then
|.(normsequence (G,ax)).| = |.(|.a.| * (normsequence (G,z))).|
by A8, A10, FINSEQ_2:9;
then A11:
|.(normsequence (G,ax)).| = |.|.a.|.| * |.(normsequence (G,z)).|
by EUCLID:11;
reconsider z = x + y as Element of product (carr G) by A1;
A12:
for i being Element of NAT st i in Seg n holds
( 0 <= (normsequence (G,z)) . i & (normsequence (G,z)) . i <= ((normsequence (G,xx)) + (normsequence (G,yy))) . i )
proof
A13:
dom xx = dom (carr G)
by CARD_3:9;
A14:
(
Seg n = dom G &
dom (carr G) = dom G )
by A2, FINSEQ_1:def 3, FINSEQ_3:29;
let i be
Element of
NAT ;
( i in Seg n implies ( 0 <= (normsequence (G,z)) . i & (normsequence (G,z)) . i <= ((normsequence (G,xx)) + (normsequence (G,yy))) . i ) )
assume A15:
i in Seg n
;
( 0 <= (normsequence (G,z)) . i & (normsequence (G,z)) . i <= ((normsequence (G,xx)) + (normsequence (G,yy))) . i )
i in dom z
by A15, A14, CARD_3:9;
hence
(
0 <= (normsequence (G,z)) . i &
(normsequence (G,z)) . i <= ((normsequence (G,xx)) + (normsequence (G,yy))) . i )
by A1, A15, A14, A13, Th8, Th9;
verum
end;
A16:
len (normsequence (G,z)) = n
by Def11;
then
len (normsequence (G,z)) = len ((normsequence (G,xx)) + (normsequence (G,yy)))
by CARD_1:def 7;
then A17:
|.(normsequence (G,z)).| <= |.((normsequence (G,xx)) + (normsequence (G,yy))).|
by A16, A12, Th2;
( ||.(x + y).|| = |.(normsequence (G,z)).| & ||.x.|| = |.(normsequence (G,xx)).| )
by Th7;
hence
( ||.(a * x).|| = |.a.| * ||.x.|| & ||.(x + y).|| <= ||.x.|| + ||.y.|| )
by A11, A17, A7, Th7, XXREAL_0:2; verum