Pseq2 is P-convergent
;
then consider z being Real such that
a3:
for e being Real st 0 < e holds
ex N1 being Nat st
for n, m being Nat st n >= N1 & m >= N1 holds
|.((Pseq2 . (n,m)) - z).| < e
;
for e being Real st 0 < e holds
ex N being Nat st
for n being Nat st n >= N holds
|.(((lim_in_cod2 Pseq2) . n) - z).| < e
proof
let e be
Real;
( 0 < e implies ex N being Nat st
for n being Nat st n >= N holds
|.(((lim_in_cod2 Pseq2) . n) - z).| < e )
assume a8:
0 < e
;
ex N being Nat st
for n being Nat st n >= N holds
|.(((lim_in_cod2 Pseq2) . n) - z).| < e
then consider N1 being
Nat such that a15:
for
n,
m being
Nat st
n >= N1 &
m >= N1 holds
|.((Pseq2 . (n,m)) - z).| < e / 2
by a3;
a12:
for
n being
Element of
NAT st
n >= N1 holds
ex
N2 being
Nat st
for
m being
Nat st
m >= N2 holds
|.(((ProjMap1 (Pseq2,n)) . m) - ((lim_in_cod2 Pseq2) . n)).| < e / 2
take
N1
;
for n being Nat st n >= N1 holds
|.(((lim_in_cod2 Pseq2) . n) - z).| < e
thus
for
n being
Nat st
n >= N1 holds
|.(((lim_in_cod2 Pseq2) . n) - z).| < e
verumproof
let n be
Nat;
( n >= N1 implies |.(((lim_in_cod2 Pseq2) . n) - z).| < e )
reconsider n1 =
n as
Element of
NAT by ORDINAL1:def 12;
assume a14:
n >= N1
;
|.(((lim_in_cod2 Pseq2) . n) - z).| < e
then consider N2 being
Nat such that a13:
for
m being
Nat st
m >= N2 holds
|.(((ProjMap1 (Pseq2,n1)) . m) - ((lim_in_cod2 Pseq2) . n1)).| < e / 2
by a12;
reconsider M =
max (
N2,
N1) as
Element of
NAT by ORDINAL1:def 12;
a17:
(ProjMap1 (Pseq2,n1)) . M = Pseq2 . (
n,
M)
by MESFUNC9:def 6;
a16:
(
M >= N2 &
M >= N1 )
by XXREAL_0:25;
a18:
|.(((lim_in_cod2 Pseq2) . n) - z).| <= |.(((lim_in_cod2 Pseq2) . n) - ((ProjMap1 (Pseq2,n1)) . M)).| + |.((Pseq2 . (n,M)) - z).|
by a17, COMPLEX1:63;
|.(((lim_in_cod2 Pseq2) . n) - ((ProjMap1 (Pseq2,n1)) . M)).| = |.(((ProjMap1 (Pseq2,n1)) . M) - ((lim_in_cod2 Pseq2) . n)).|
by COMPLEX1:60;
then a20:
|.(((lim_in_cod2 Pseq2) . n) - ((ProjMap1 (Pseq2,n1)) . M)).| < e / 2
by a13, XXREAL_0:25;
|.((Pseq2 . (n1,M)) - z).| < e / 2
by a15, a16, a14;
then
|.(((lim_in_cod2 Pseq2) . n) - ((ProjMap1 (Pseq2,n1)) . M)).| + |.((Pseq2 . (n,M)) - z).| < (e / 2) + (e / 2)
by a20, XREAL_1:8;
hence
|.(((lim_in_cod2 Pseq2) . n) - z).| < e
by a18, XXREAL_0:2;
verum
end;
end;
hence
lim_in_cod2 Pseq2 is convergent
by SEQ_2:def 6; verum