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We show that every complete metric space is homeomorphic to the precise locus of zeros of an entire analytic map from a Hilbert space to a Banach space. As a corollary, every complete separable metric space is homeomorphic to the precise…

dg-ga · Mathematics 2008-02-03 Vladimir Pestov

Working in the framework of Borel reducibility, we study various notions of embeddability between groups. We prove that the embeddability between countable groups, the topological embeddability between (discrete) Polish groups, and the…

Logic · Mathematics 2018-02-08 Filippo Calderoni , Luca Motto Ros

We study the complexity of isomorphism of classes of metric structures using methods from infinitary continuous logic. For Borel classes of locally compact structures, we prove that if the equivalence relation of isomorphism is potentially…

Logic · Mathematics 2021-09-20 Andreas Hallbäck , Maciej Malicki , Todor Tsankov

A topological space is almost locally compact if it contains a dense locally compact subspace. We generalize a result from \cite{Ma}, showing that isomorphism on Borel classes of almost locally compact Polish metric structures is always…

Logic · Mathematics 2025-08-12 Maciej Malicki

Classes of Banach spaces that are finitely, strongly finitely or elementary equivalent are introduced. On sets of these classes topologies are defined in such a way that sets of defined classes become compact totally disconnected…

Functional Analysis · Mathematics 2007-05-23 Eugene Tokarev

A problem of Banach asks whether every infinite-dimensional Banach space which is isomorphic to all its infinite-dimensional subspaces must be isomorphic to a separable Hilbert space. In this paper we prove a result of a Ramsey-theoretic…

Functional Analysis · Mathematics 2007-05-23 W. T. Gowers

We compute here the Borel complexity of the relation of isometry between separable Banach spaces, using results of Gao, Kechris and Weaver.

Functional Analysis · Mathematics 2007-05-23 Julien Melleray

We provide a complete classification, up to order-isomorphism, of all possible Wadge hierarchies on zero-dimensional Polish spaces using (essentially) countable ordinals as complete invariants. We also observe that although our assignment…

Logic · Mathematics 2023-05-17 Raphaël Carroy , Luca Motto Ros , Salvatore Scamperti

We prove the result stated in the title. This provides a first example of an infinite-dimensional Banach space whose Lipschitz free space is isomorphic to the free space of a compact set.

Functional Analysis · Mathematics 2019-11-14 Luis C. García-Lirola , Antonin Prochazka

A Banach space has the Schur property when every weakly convergent sequence converges in norm. We prove a Schur-like property for measures: if a sequence of finite signed Borel measures on a Polish space is such that it is bounded in total…

Functional Analysis · Mathematics 2018-12-18 Sander C. Hille , Tomasz Szarek , Daniel T. H. Worm , Maria Ziemlanska

For each sequence X of finite-dimensional Banach spaces there exists a sequence H of finite connected nweighted graphs with maximum degree 3 such that the following conditions on a Banach space Y are equivalent: (1) Y admits uniformly…

Functional Analysis · Mathematics 2013-12-18 Mikhail I. Ostrovskii

We prove a structural property of the class of unconditionally saturated separable Banach spaces. We show, in particular, that for every analytic set $\aaa$, in the Effros-Borel space of subspaces of $C[0,1]$, of unconditionally saturated…

Functional Analysis · Mathematics 2010-06-15 Pandelis Dodos , Jordi Lopez-Abad

We construct a family of separable Hilbertian operator spaces, such that the relation of complete isomorphism between the subspaces of each member of this family is complete $\ks$. We also investigate some interesting properties of…

Functional Analysis · Mathematics 2010-09-21 Timur Oikhberg , Christian Rosendal

This paper contains results concerning the Borel reduction of the relation $E_0$ of eventual agreement between sequences of 0's and 1's, to the relation of permutative equivalence between basic sequences in a Banach space. For more clarity…

Functional Analysis · Mathematics 2007-05-23 Valentin Ferenczi

We study the interplay between Banach space theory and theory of analytic P-ideals. Applying the observation that, up to isomorphism, all Banach spaces with unconditional bases can be constructed in a way very similar to the construction of…

Logic · Mathematics 2019-06-03 Piotr Borodulin-Nadzieja , Barnabás Farkas

We prove several dichotomies on linear embeddings between Banach spaces. Given an arbitrary Banach space X with a basis, we show that the relations of isomorphism and bi-embedding are meager or co-meager on the Polish set of block-subspaces…

Functional Analysis · Mathematics 2011-11-29 Valentin Ferenczi , Gilles Godefroy

We show that the classes of separable reflexive Banach spaces and of spaces with separable dual are strongly bounded. This gives a new proof of a recent result of E. Odell and Th. Schlumprecht, asserting that there exists a separable…

Functional Analysis · Mathematics 2007-05-23 Pandelis Dodos , Valentin Ferenczi

We extend a theorem of Kato on similarity for sequences of projections in Hilbert spaces to the case of isomorphic Schauder decompositions in certain Banach spaces. To this end we use $\ell_{\Psi}$-Hilbertian and $\infty$-Hilbertian…

Functional Analysis · Mathematics 2013-09-26 Vitalii Marchenko

Following results of Bourgain and Gorelik we show that the spaces $\ell_p$, $1<p<\infty$, as well as some related spaces have the following uniqueness property: If $X$ is a Banach space uniformly homeomorphic to one of these spaces then it…

Functional Analysis · Mathematics 2009-09-25 William B. Johnson , Joram Lindenstrauss , Gideon Schechtman

This article is a continuation of a paper of the first author \cite{F} about complex structures on real Banach spaces. We define a notion of even infinite dimensional real Banach space, and prove that there exist even spaces, including HI…

Functional Analysis · Mathematics 2007-05-23 Valentin Ferenczi , Eloi Medina Galego