Submission date: 20 September 2016

Abstract:

We give a criterion ensuring that the elementary class of a modular Banach space E (that is, the class of Banach spaces, some ultrapower of which is linearly isometric to an ultrapower of E) consists of all direct sums E\oplus_m H, where H is an arbitrary Hilbert space and \oplus_m denotes the modular direct sum. Also, we give several families of examples in the class of Nakano direct sums of finite dimensional normed spaces that satisfy this criterion. This yields many new examples of uncountably categorical Banach spaces, in the model theory of Banach space structures.

Mathematics Subject Classification: 46B04, 46B45 (Primary), 03C20, 03C35 (Secondary)

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Full text arXiv 1606.03122: pdf, ps.