Grothendieck ideals of $\ell_\infty$
Abstract
We answer several questions in the literature concerning the Grothendieck property of ideals of the Banach lattice that contain . Any such ideal can be represented as a space for an ideal over the natural numbers. We provide a characterization of when is a Grothendieck space in terms of finitely additive measures over and elements of . Using this characterization we show that there are analytic ideals such that is Grothendieck. In the opposite direction we show that for any AD family , and are not Grothendieck spaces, and that for most of the Borel ideals present in the literature, is not Grothendieck. In particular, the family of ideals that do not have the Grothendieck property is cofinal in the Rudin-Keisler order, so the Grothendieck property is not downward closed in the Kat\v{e}tov order. Continuing the work in \cite{Sobota-Zuchowski, Zuchowski}, we also provide similar results on the Nikodym property of the Boolean subalgebras of generated by the ideal .
Keywords
Cite
@article{arxiv.2607.25095,
title = {Grothendieck ideals of $\ell_\infty$},
author = {Michael Hrusák and Michael A. Rincón-Villamizar and Luis Sáenz and Carlos Uzcátegui Aylwin},
journal= {arXiv preprint arXiv:2607.25095},
year = {2026}
}