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Arbiter
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Dominated Convergence Theorem for Banach limits

The notion of a Banach limit is usually defined for the space of bounded sequences, but one can define it for more general spaces, see What is a generalized limit?, Do multiplicative Banach limits exist? and references therein.

I am interested in the Banach space of Bounded functions $f: \mathbb{R}_+ \to \mathbb{C}$ with $ ||f|| = \rm sup_{t \in \mathbb{R}_+} |f(t)| $ and Banach limits on it. Consider a sequence $f_n(t)$ ,$n\in \mathbb{N}$, of such functions and a Banach limit denoted by $L$. Suppose that for all $t\in \mathbb{R}_+$: $\sum_{n=1}^\infty f_n(t)$ exists, and consider its Banach limit $$L\big( \sum_{n=1}^{\infty} f_n(t) \big) $$ Is it true that $$L\big( \sum_{n=1}^{\infty} f_n(t) \big) = \sum_{n=1}^{\infty}L\big( f_n(t) \big) $$

for all Banach limits $L$?

With usual limits, i.e.\ $\lim_{t\to \infty} \lim_N \sum_{n=1}^N f_n(t) $, it's not always the case that we can commute the two limits.

So, does the dominated convergence theorem extend to Banach limits, so that the Banach limit $L$ can be moved inside the summation/commute the limits? Under what assumptions?

I'd appreciate references.

Arbiter
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