Let `1 and c denote the Banach spaces of real bounded and convergent sequences
x = (xn) normed by kxk = sup
n
jxnj ; respectively.
Let be a one to one mapping of the set of positive integers into itself such that
k
(n) =
k1
(n)
; k = 1; 2; ::: .A continuous linear functional ' on `1 is said
to be an invariant mean or a mean if and only if
(i) ' (x) 0 when xn 0 for all n;
(ii) ' (e) = 1; where e = (1; 1; 1; :::) and
(iii) '
x(n)
= ' (fxng) for all x 2 `1:
If is the translation mapping n ! n + 1; a mean is often called a Banach
limit [3], and V is the set of convergent sequences, that is, the set of bounded
sequences all of whose invariant means are equal, is the set ^f of almost convergent
sequences
Primary Language | English |
---|---|
Subjects | Mathematical Sciences |
Journal Section | Research Articles |
Authors | |
Publication Date | February 1, 2018 |
Submission Date | May 12, 2014 |
Published in Issue | Year 2018 Volume: 67 Issue: 1 |
Communications Faculty of Sciences University of Ankara Series A1 Mathematics and Statistics.
This work is licensed under a Creative Commons Attribution 4.0 International License.