A characterization of the Schur property by means of the Bohr topology
✍ Scribed by Salvador Hernández; Jorge Galindo; Sergio Macario
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 101 KB
- Volume
- 97
- Category
- Article
- ISSN
- 0166-8641
No coin nor oath required. For personal study only.
✦ Synopsis
Let G be a MAPA group that is metrizable and satisfies Pontryagin duality; that is, it coincides with its topological bidual. We prove that the Bohr topology of G respects compactness if and only if every non-totally bounded subset contains an infinite discrete subset which is C * -embedded in the Bohr compactification of G. This result is used to characterize the Banach spaces which respect compactness, or, with a different terminology, have the Schur property (defined below). Among other equivalent properties, we prove that a Banach space E has the Schur property if and only if every bounded basic sequence contains an infinite subsequence equivalent to a l 1 -basis.
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The Schur-convexity at the upper and lower limits of the integral for the mean of a convex function is researched. As applications, a form with a parameter of Stolarsky's mean is obtained and a relevant double inequality that is an extension of a known inequality is established.