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On Pelczynski’s property u for Banach spaces. (English) Zbl 0661.46014

A Banach space X is said to have property u if corresponding to each weak Cauchy sequence \((x_ n)\) there exists a sequence \((y_ n)\) such that \(\sum y_ n\) is weakly unconditionally Cauchy and \((\sum x_ n- \sum^{n}_{1}y_ i)\) converges weakly to 0; we then write \(X\in u\). Using an earlier result [J. Howard and K. Melendez, Bull. Aust. Math. Soc. 7, 183-190 (1972; Zbl 0244.47011)] the author observes that if X is wealy sequentially complete then \(X\in u\). The following results are obtained:
(a) \(\ell_{\infty}\not\in u.\)
(b) If \(X\in u\) is a conjugate space then X is wealy sequentially complete.
Reviewer: R.Gross

MSC:

46B20 Geometry and structure of normed linear spaces

Citations:

Zbl 0244.47011
Full Text: DOI

References:

[1] C. Bessaga and A. Pelczynski, On bases and unconditional convergence of series in Banach spaces,Studia Math.,17 (1958), 151–164. · Zbl 0084.09805
[2] J. Howard and K. Melendez, Sufficient conditions for a continuous linear operator to be weakly compact,Bull. Aust. Math. Soc.,7 (1972), 183–190. · Zbl 0244.47011 · doi:10.1017/S0004972700044968
[3] R. D. McWilliams, On thew *-sequential closure of subspaces of Banach spaces,Port. Math.,22 (1963), 209–214. · Zbl 0132.08904
[4] A. Pelczynski, A connection between weakly unconditional convergence and weakly completeness of Banach spaces,Bull. Acad. Polon. Sci. Sér. Sci. Math. Astronom. Phys.,7 (1958), 251–253. · Zbl 0082.10804
[5] I. Singer,Bases in Banach spaces I, Springer-Verlag (New York and Berlin, 1970). · Zbl 0198.16601
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