The Szlenk Index and the Fixed Point Property under Renorming
نویسندگان
چکیده
Assume that X is a Banach space such that its Szlenk index Sz X is less than or equal to the first infinite ordinal ω. We prove that X can be renormed in such a way that X with the resultant norm satisfies R X < 2, where R · is the Garcı́a-Falset coefficient. This leads us to prove that if X is a Banach space which can be continuously embedded in a Banach space Y with Sz Y ≤ ω, then, X can be renormed to satisfy the w-FPP. This result can be applied to Banach spaces which can be embedded in C K , where K is a scattered compact topological space such that K ω ∅. Furthermore, for a Banach space X, ‖ · ‖ , we consider a distance in the space P of all norms in X which are equivalent to ‖ · ‖ for which P becomes a Baire space . If Sz X ≤ ω, we show that for almost all norms in the sense of porosity in P, X satisfies the w-FPP. For general reflexive spaces independently of the Szlenk index , we prove another strong generic result in the sense of Baire category.
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