Structure of normal cones contained in a Banach space or its dual. II. (Structure des cones normaux contenus dans un espace de Banach ou son dual. II.) (French) Zbl 0802.46030
Author’s abstract: Let \(B\) be a Banach space and \(X\subset B\) a normal cone such that the norm is monotone on \(X\) for the order determined by \(X\). We study the sup, denoted by \(i(X)\), of the \(q\geq 1\) such that, for each \(\varepsilon>0\) and each \(n\), there are \(x_ 1,\dots, x_ n\) in \(X\) such that:
\[
(1-\varepsilon) \| (a_ k)\|_ q\leq \Biggl\| \sum_ 1^ n a_ k x_ k \Biggr\| \leq (1+\varepsilon) \| (a_ k)\|_ q,
\]
for all \(a_ 1,\dots, a_ n \geq 0\), where \(\|\;\|_ q\) is the norm in \(\ell^ q\). We prove that \(i(X)\) is the inf of the \(p\) for which we have:
\[
\Biggl( \sum_ 1^ n \| x_ k\|^ p \Biggr)^{1/p}\leq S_ p \Biggl\| \sum_ 1^ n x_ k \Biggr\| \qquad \text{for all } x_ 1,\dots, x_ n \text{ in } X.
\]
The proof uses a similar theorem of J. L. Krivine [Ann. Math., II. Ser. 104, 1-29 (1976; Zbl 0329.46008)] concerning Banach Riesz spaces. Here conical measures are a useful tool. We establish a link with a preceding work in which we adapt the Maurey theory of factorization of operators with values in a \(L^ p\)-space, to the case of normal cones, contained in a Banach space.
[For part I see C. R. Acad. Sci., Paris, Sér. I 314, No. 7, 535-539 (1992; Zbl 0765.46009)].
[For part I see C. R. Acad. Sci., Paris, Sér. I 314, No. 7, 535-539 (1992; Zbl 0765.46009)].
Reviewer: A.L.Brown (Newcastle upon Tyne)
MSC:
46B40 | Ordered normed spaces |
47A68 | Factorization theory (including Wiener-Hopf and spectral factorizations) of linear operators |
46B15 | Summability and bases; functional analytic aspects of frames in Banach and Hilbert spaces |
46B20 | Geometry and structure of normed linear spaces |
Keywords:
summary; normal cone; Banach Riesz spaces; conical measures; Maurey theory; factorization of operators with values in a \(L^ p\)-spaceReferences:
[1] | Schaeffer, Topological vector spaces (1977) |
[2] | DOI: 10.2307/1971054 · Zbl 0329.46008 · doi:10.2307/1971054 |
[3] | Becker, C.R. Acad. Sci. Paris Sér I Math 314 pp 535– (1992) |
[4] | Choquet, Lectures on analysis 1–3, Mathematics (1969) · Zbl 0181.39601 |
[5] | Fakhoury, Pacific J. Math. 39 pp 641– (1971) · doi:10.2140/pjm.1971.39.641 |
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