English

Generic properties of l_p-contractions and similar operator topologies

Functional Analysis 2022-10-28 v2

Abstract

If XX is a separable reflexive Banach space, there are several natural Polish topologies on B(X)\mathcal{B}(X), the set of contraction operators on XX (none of which being clearly ``more natural'' than the others), and hence several a priori different notions of genericity -- in the Baire category sense -- for properties of contraction operators. So it makes sense to investigate to which extent the generic properties, i.e. the comeager sets, really depend on the chosen topology on B(X)\mathcal{B}(X). In this paper, we focus on p\ell_p\,-\,spaces, 1<p2<1<p\neq 2<\infty. We show that for some pairs of natural Polish topologies on B1(p)\mathcal B_1(\ell_p), the comeager sets are in fact the same; and our main result asserts that for p=3p=3 or 3/23/2 and in the real case, all topologies on B1(p)\mathcal B_1(\ell_p) lying between the Weak Operator Topology and the Strong^* Operator Topology share the same comeager sets. Our study relies on the consideration of continuity points of the identity map for two different topologies on B1(p)\mathcal{B}_1 (\ell_p). The other essential ingredient in the proof of our main result is a careful examination of norming vectors for finite-dimensional contractions of a special type.

Keywords

Cite

@article{arxiv.2207.07938,
  title  = {Generic properties of l_p-contractions and similar operator topologies},
  author = {Sophie Grivaux and Etienne Matheron and Quentin Menet},
  journal= {arXiv preprint arXiv:2207.07938},
  year   = {2022}
}

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