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    Duality on Banach spaces and a Borel parametrized version of Zippin's theorem

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    Let SB be the standard coding for separable Banach spaces as subspaces of C(Δ)C(\Delta). In these notes, we show that if B⊂SB\mathbb{B} \subset \text{SB} is a Borel subset of spaces with separable dual, then the assignment X↦X∗X \mapsto X^* can be realized by a Borel function B→SB\mathbb{B}\to \text{SB}. Moreover, this assignment can be done in such a way that the functional evaluation is still well defined (Theorem 11). Also, we prove a Borel parametrized version of Zippin's theorem, i.e., we prove that there exists Z∈SBZ \in \text{SB} and a Borel function that assigns for each X∈BX \in \mathbb{B} an isomorphic copy of XX inside of ZZ (Theorem 55)
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