English

Similar operator topologies on the space of positive contractions

Functional Analysis 2025-11-25 v2

Abstract

In this article, we study the similarity of the Polish operator topologies WOT\texttt{WOT}, SOT\texttt{SOT}, \texttt{SOT}\mbox{_{*}} and \texttt{SOT}\mbox{^{*}} on the set of the positive contractions on p\ell_p with p>1p > 1. Using the notion of norming vector for a positive operator, we prove that these topologies are similar on P1(2)\mathcal{P}_1(\ell_2), that is, they have the same dense sets in P1(2)\mathcal{P}_1(\ell_2). In particular, these topologies will share the same comeager sets in P1(2)\mathcal{P}_1(\ell_2). We then apply these results to the study of typical properties of positive contractions on p\ell_p-spaces in the Baire category sense. In particular, we prove that a typical positive contraction T(P1(2),SOT)T \in (\mathcal{P}_1(\ell_2), \texttt{SOT}) has no eigenvalue. This stands in strong contrast to a result of Eisner and M\'atrai, stating that the point spectrum of a typical contraction T(B1(2),SOT)T \in (\mathcal{B}_1(\ell_2), \texttt{SOT}) contains the whole unit disk. As a consequence of our results, we obtain that a typical positive contraction T(P1(2),WOT)T \in (\mathcal{P}_1(\ell_2), \texttt{WOT}) (resp. T \in (\mathcal{P}_1(\ell_2), \texttt{SOT}\mbox{_{*}})) has no eigenvalue.

Keywords

Cite

@article{arxiv.2412.11587,
  title  = {Similar operator topologies on the space of positive contractions},
  author = {Valentin Gillet},
  journal= {arXiv preprint arXiv:2412.11587},
  year   = {2025}
}

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21 pages