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A problem on spreading models

1996/07/12 by Odell, Edward, Schlumprecht, Thomas
#46B45 #FOS: Mathematics #Functional Analysis (math.FA)

paper · doi:10.48550/arxiv.math/9607207

Abstract

It is proved that if a Banach space X has a basis (en) satisfying every spreading model of a normalized block basis of (en) is 1-equivalent to the unit vector basis of ℓ1 (respectively, c0) then X contains ℓ1 (respectively, c0). Furthermore Tsirelson's space T is shown to have the property that every infinite dimensional subspace contains a sequence having spreading model 1-equivalent to the unit vector basis of ℓ1. An equivalent norm is constructed on T so that ‖s1+s2‖<2 whenever (sn) is a spreading model of a normalized basic sequence in T.

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