{ "id": "1905.12455", "version": "v1", "published": "2019-05-29T13:44:06.000Z", "updated": "2019-05-29T13:44:06.000Z", "title": "A $ΞΎ$-weak Grothendieck compactness principle", "authors": [ "Kevin Beanland", "R. M. Causey" ], "categories": [ "math.FA" ], "abstract": "For $0\\leqslant \\xi\\leqslant \\omega_1$, we define the notion of $\\xi$-weakly precompact and $\\xi$-weakly compact sets in Banach spaces and prove that a set is $\\xi$-weakly precompact if and only if its weak closure is $\\xi$-weakly compact. We prove a quantified version of Grothendieck's compactness principle and the characterization of Schur spaces obtained by Dowling et al. For $0\\leqslant \\xi\\leqslant \\omega_1$, we prove that a Banach space $X$ has the $\\xi$-Schur property if and only if every $\\xi$-weakly compact set is contained in the closed, convex hull of a weakly null (equivalently, norm null) sequence.", "revisions": [ { "version": "v1", "updated": "2019-05-29T13:44:06.000Z" } ], "analyses": { "keywords": [ "weak grothendieck compactness principle", "weakly compact set", "banach space", "weakly precompact", "grothendiecks compactness principle" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }