Abstract

For vector lattices E and F, where F is Dedekind complete and supplied with a locally solid topology, we introduce the corresponding locally solid absolute strong operator topology on the order bounded operators {mathscr{L}}_{mathrm{ob}}(E,F) from E into F. Using this, it follows that {mathscr{L}}_{mathrm{ob}}(E,F) admits a Hausdorff uo-Lebesgue topology whenever F does. For each of order convergence, unbounded order convergence, and—when applicable—convergence in the Hausdorff uo-Lebesgue topology, there are both a uniform and a strong convergence structure on {mathscr{L}}_{mathrm{ob}}(E,F). Of the six conceivable inclusions within these three pairs, only one is generally valid. On the orthomorphisms of a Dedekind complete vector lattice, however, five are generally valid, and the sixth is valid for order bounded nets. The latter condition is redundant in the case of sequences of orthomorphisms, as a consequence of a uniform order boundedness principle for orthomorphisms that we establish. We furthermore show that, in contrast to general order bounded operators, orthomorphisms preserve not only order convergence of nets, but unbounded order convergence and—when applicable—convergence in the Hausdorff uo-Lebesgue topology as well.

Highlights

  • Introduction and overviewLet X be a non-empty set

  • A convergence structure on X is a non-empty collection C of pairs ((x ) ∈A, x), where (x ) ∈A is a net in X and x ∈ X, such that: 1. when ((x ) ∈A, x) ∈ C, ((x ) ∈B, x) ∈ C for every subnet (x ) ∈B of (x ) ∈A; 2. when a net (x ) ∈A in X is constant with value x, ((x ) ∈A, x) ∈ C

  • We shall not pursue this in the present paper, let us still mention that the inclusion of the subnet criterion in the definition makes it possible to introduce an associated topology on X in a natural way

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Summary

Introduction and overview

The present paper is primarily concerned with the possible inclusions between the uniform and strong convergence structure for each of order convergence, unbounded order convergence, and—when applicable—convergence in the Hausdorff uo-Lebesgue topology. Is it true that a uniformly order convergent net of order bounded operators is strongly order convergent? It has been known long since that more than one topology on a von Neumann algebra is needed to understand it and its role in representation theory on Hilbert spaces, and the same holds true for the convergence structures as related to these commutants in an ordered context Using these convergence structures, it is, for example, possible to obtain ordered versions of von Neumann’s bicommutant theorem.

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Preliminaries
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Orthomorphisms
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Continuity properties of orthomorphisms
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Full Text
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