Infinite Asymptotic Games and (*)-Embeddings of Banach Spaces

• Autorzy: Georgios-Nektarios I. Karadakis
• Języki publikacji: EN

Abstrakty

EN

We use methods of infinite asymptotic games to characterize subspaces of Banach spaces with a finite-dimensional decomposition (FDD) and prove new theorems on operators. We consider a separable Banach space X, a set 𝓢 of sequences of finite subsets of X and the 𝓢-game. We prove that if 𝓢 satisfies some specific stability conditions, then Player I has a winning strategy in the 𝓢-game if and only if X has a skipped-blocking decomposition each of whose skipped-blockings belongs to 𝓢. This result implies that if T is a (*)-embedding of X (a 1-1 operator which maps the balls of subspaces with an FDD to weakly $G_{δ}$ sets), then, for every n ≥ 4, there exist n subspaces of X with an FDD that generate X and the restriction of T to each of them is a semi-embedding under an equivalent norm. We also prove that X does not contain isomorphic copies of dual spaces if and only if every (*)-embedding defined on X is an isomorphic embedding. We also deal with the case where X is non-separable, reaching similar results.

Kategorie tematyczne

• 46B20: Geometry and structure of normed linear spaces
• 46B03: Isomorphic theory (including renorming) of Banach spaces

• Wydawca: Institute of Mathematics Polish Academy of Sciences
• Czasopismo: Bulletin of the Polish Academy of Sciences. Mathematics
• Rocznik: 2012
• Tom: 60
• Numer: 2
• Strony: 133-154

Daty

wydano

2012

Twórcy

autor

Georgios-Nektarios I. Karadakis

• 14, Bizaniou Str., 164 51 Argiroupoli, Athens, Greece

Identyfikatory

DOI

10.4064/ba60-2-4