We prove that every bounded, uniformly separated sequence in a normed space contains a “uniformly independent” subsequence (see definition); the constants involved do not depend on the sequence or the space. The finite version of this result is true for all quasinormed spaces. We give a counterexample to the infinite version in for each 0 < p < 1. Some consequences for nonstandard topological vector spaces are derived.
@article{bwmeta1.element.bwnjournal-article-smv124i1p81bwm, author = {C. Henson and Nigel Kalton and N. Peck and Ign\'ac Tere\v s\v c\'ak and Pavol Zlato\v s}, title = {Some Ramsey type theorems for normed and quasinormed spaces}, journal = {Studia Mathematica}, volume = {122}, year = {1997}, pages = {81-100}, zbl = {0918.46005}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-smv124i1p81bwm} }
Henson, C.; Kalton, Nigel; Peck, N.; Tereščák, Ignác; Zlatoš, Pavol. Some Ramsey type theorems for normed and quasinormed spaces. Studia Mathematica, Tome 122 (1997) pp. 81-100. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-smv124i1p81bwm/
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