let X be Complex_Banach_Algebra; :: thesis: for z, w being Element of X
for seq being sequence of X st ( for k being Element of NAT holds seq . k = (Partial_Sums (Conj (k,z,w))) . k ) holds
( seq is convergent & lim seq = 0. X )

let z, w be Element of X; :: thesis: for seq being sequence of X st ( for k being Element of NAT holds seq . k = (Partial_Sums (Conj (k,z,w))) . k ) holds
( seq is convergent & lim seq = 0. X )

deffunc H1( Element of NAT ) -> Element of REAL = (Partial_Sums ||.(Conj ($1,z,w)).||) . $1;
ex rseq being Real_Sequence st
for k being Element of NAT holds rseq . k = H1(k) from SEQ_1:sch 1();
then consider rseq being Real_Sequence such that
A1: for k being Element of NAT holds rseq . k = (Partial_Sums ||.(Conj (k,z,w)).||) . k ;
let seq be sequence of X; :: thesis: ( ( for k being Element of NAT holds seq . k = (Partial_Sums (Conj (k,z,w))) . k ) implies ( seq is convergent & lim seq = 0. X ) )
assume A2: for k being Element of NAT holds seq . k = (Partial_Sums (Conj (k,z,w))) . k ; :: thesis: ( seq is convergent & lim seq = 0. X )
A3: now
let k be Element of NAT ; :: thesis: ||.(seq . k).|| <= (Partial_Sums ||.(Conj (k,z,w)).||) . k
||.(seq . k).|| = ||.((Partial_Sums (Conj (k,z,w))) . k).|| by A2;
hence ||.(seq . k).|| <= (Partial_Sums ||.(Conj (k,z,w)).||) . k by Th10; :: thesis: verum
end;
A4: now
let k be Element of NAT ; :: thesis: ||.(seq . k).|| <= rseq . k
||.(seq . k).|| <= (Partial_Sums ||.(Conj (k,z,w)).||) . k by A3;
hence ||.(seq . k).|| <= rseq . k by A1; :: thesis: verum
end;
A5: now
let p be real number ; :: thesis: ( p > 0 implies ex n being Element of NAT st
for k being Element of NAT st n <= k holds
abs ((rseq . k) - 0) < p )

assume p > 0 ; :: thesis: ex n being Element of NAT st
for k being Element of NAT st n <= k holds
abs ((rseq . k) - 0) < p

then consider n being Element of NAT such that
A6: for k being Element of NAT st n <= k holds
abs ((Partial_Sums ||.(Conj (k,z,w)).||) . k) < p by Th31;
take n = n; :: thesis: for k being Element of NAT st n <= k holds
abs ((rseq . k) - 0) < p

now
let k be Element of NAT ; :: thesis: ( n <= k implies abs ((rseq . k) - 0) < p )
assume A7: n <= k ; :: thesis: abs ((rseq . k) - 0) < p
abs ((rseq . k) - 0) = abs ((Partial_Sums ||.(Conj (k,z,w)).||) . k) by A1;
hence abs ((rseq . k) - 0) < p by A6, A7; :: thesis: verum
end;
hence for k being Element of NAT st n <= k holds
abs ((rseq . k) - 0) < p ; :: thesis: verum
end;
then A8: rseq is convergent by SEQ_2:def 6;
then lim rseq = 0 by A5, SEQ_2:def 7;
hence ( seq is convergent & lim seq = 0. X ) by A4, A8, Th12; :: thesis: verum