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1-spreading models in mixed Tsirelson space

Denny H. Leung, Wee-Kee Tang

math.FAarXiv:math/0303375

Abstract

Suppose that (Fn)n=1∞ is a sequence of regular families of finite subsets of N and (θn)n=1∞ is a nonincreasing null sequence in (0,1). The mixed Tsirelson space T[(θn, Fn)n=1∞] is the completion of c00 with respect to the implicitly defined norm ||x|| = max||x||c0, supn sup θn Σi=1j||Eix||, where the last supremum is taken over all finite subsets E1,...,Ej of N such that E1 < >... <Ej and min E1,...,min Ej ∈ Fn. Necessary and sufficient conditions are obtained for the existence of higher order 1-spreading models in every subspace generated by a subsequence of the unit vector basis of T[(θn, Fn)n=1∞.

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