English

A note on the Schur and Phillips lemmas

Functional Analysis 2022-08-30 v1 General Topology

Abstract

It is well-known that every weakly convergent sequence in 1\ell_1 is convergent in the norm topology (Schur's lemma). Phillips' lemma asserts even more strongly that if a sequence (μn)nN(\mu_n)_{n\in\mathbb N} in \ell_\infty' converges pointwise on {0,1}N\{0,1\}^\mathbb N to 00, then its 1\ell_1-projection converges in norm to 00. In this note we show how the second category version of Schur's lemma, for which a short proof is included, can be used to replace in Phillips' lemma {0,1}N\{0,1\}^\mathbb N by any of its subsets which contains all finite sets and having some kind of interpolation property for finite sets.

Cite

@article{arxiv.2208.13468,
  title  = {A note on the Schur and Phillips lemmas},
  author = {Ahmed Bouziad},
  journal= {arXiv preprint arXiv:2208.13468},
  year   = {2022}
}

Comments

To appear in Topology and its Applications

R2 v1 2026-06-25T02:03:00.371Z