Metric unconditionality and Fourier analysis
نویسندگان
چکیده
منابع مشابه
Metric unconditionality and Fourier analysis
We study several functional properties of isometric and almost isometric unconditionality and state them as a property of families of multipliers. The most general such notion is that of “metric unconditional approximation property”. We characterize this “(umap)” by a simple property of “block unconditionality” for spaces with nontrivial cotype. We focus on subspaces of Banach spaces of functio...
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J. Elton proved that for δ ∈ (0, 1] there exists K(δ) <∞ such that every normalized weakly null sequence in a Banach space admits a subsequence (xi) with the following property: if ai ∈ [−1, 1] for all i∈N and E⊂{i∈N : |ai|≥ δ}, then ‖ ∑ i∈E aixi‖≤K(δ)‖ ∑ i aixi‖. It is unknown if supδ>0 K(δ) < ∞. This problem turns out to be closely related to the question whether every infinite-dimensional Ba...
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ژورنال
عنوان ژورنال: Studia Mathematica
سال: 1998
ISSN: 0039-3223,1730-6337
DOI: 10.4064/sm-131-1-19-62