We prove that if is a seminormalized basic sequence and X is a Banach space such that every normalized weakly null sequence in X has a subsequence that is dominated by , then there exists a uniform constant C ≥ 1 such that every normalized weakly null sequence in X has a subsequence that is C-dominated by . This extends a result of Knaust and Odell, who proved this for the cases in which is the standard basis for or c₀.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-sm184-1-4, author = {Daniel Freeman}, title = {Weakly null sequences with upper estimates}, journal = {Studia Mathematica}, volume = {187}, year = {2008}, pages = {79-102}, zbl = {1140.46303}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm184-1-4} }
Daniel Freeman. Weakly null sequences with upper estimates. Studia Mathematica, Tome 187 (2008) pp. 79-102. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm184-1-4/