New proofs of Rosenthal’s l–theorem and the Josefson–Nissenzweig theorem
نویسنده
چکیده
We give elementary proofs of the theorems mentioned in the title. Our methods rely on a simple version of Ramsey theory and a martingale difference lemma. They also provide quantitative results: if a Banach space contains l only with a bad constant then every bounded sequence admits a subsequence which is “nearly” a weak Cauchy sequence.
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تاریخ انتشار 1994