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The main result of this paper is that the space of conformally compact Einstein metrics on a given manifold is a smooth, infinite dimensional Banach manifold, provided it is non-empty, generalizing earlier work of Graham-Lee and Biquard. We…

Differential Geometry · Mathematics 2010-03-16 Michael T. Anderson

We study embeddings between reproducing kernel Hilbert spaces $H(K)$ of functions of $d \in \mathbb{N} \cup \{\infty\}$ variables. The kernels $K$ are superpositions of weighted finite tensor products of a fixed univariate kernel. The basic…

Numerical Analysis · Mathematics 2026-05-01 Michael Gnewuch , Peter Kritzer , Klaus Ritter

The paper alluded to in the title contains the following striking result: Let $I$ be the unit interval and $\Delta$ the Cantor set. If $X$ is a quasi Banach space containing no copy of $c_0$ which is isomorphic to a closed subspace of a…

Functional Analysis · Mathematics 2021-05-28 Félix Cabello Sánchez

A topological space $X$ is called $\Cal A$-real compact, if every algebra homomorphism from $\Cal A$ to the reals is an evaluation at some point of $X$, where $\Cal A$ is an algebra of continuous functions. Our main interest lies on…

Functional Analysis · Mathematics 2016-09-06 Andreas Kriegl , Peter W. Michor

In this note we study the structure of Lipschitz-free Banach spaces. We show that every Lipschitz-free Banach space over an infinite metric space contains a complemented copy of $\ell_1$. This result has many consequences for the structure…

Functional Analysis · Mathematics 2018-02-09 Marek Cuth , Michal Doucha , Przemyslaw Wojtaszczyk

We conjecture that whenever $M$ is a metric space of density at most continuum, then the space of Lipschitz functions is $w^*$-separable. We prove the conjecture for several classes of metric spaces including all the Banach spaces with a…

Functional Analysis · Mathematics 2025-03-14 Leandro Candido , Marek Cuth , Benjamin Vejnar

We prove that the Lipschitz-free space over a countable compact metric space is isometric to a dual space and has the metric approximation property.

Functional Analysis · Mathematics 2014-04-16 Aude Dalet

The space of unitary $C_{0}$-semigroups on separable infinite dimensional Hilbert space, when viewed under the topology of uniform weak convergence on compact subsets of $\mathbb{R}_{+}$, is known to admit various interesting residual…

Functional Analysis · Mathematics 2023-02-02 Raj Dahya

We extend the classical Mercer theorem to reproducing kernel Hilbert spaces whose elements are functions from a measurable space $X$into $\mathbb C^n$. Given a finite measure $\mu$ on $X$, we represent the reproducing kernel $K$ as…

Functional Analysis · Mathematics 2011-10-19 Ernesto De Vito , Veronica Umanita` , Silvia Villa

We prove a compact embedding theorem in a class of spaces of piecewise H1 functions subordinated to a class of shape regular, but not necessarily quasi-uniform triangulations of a polygonal domain. This result generalizes the…

Numerical Analysis · Mathematics 2013-03-01 Sheng Zhang

We construct infinitely differentiable norms and partitions of unity for a class of Banach spaces which includes all spaces $\C(K)$ with $K$ a countable compact space, and all spaces $\C_0[0,\Omega )$ with $\Omega $ an ordinal.

Functional Analysis · Mathematics 2008-02-03 Richard Haydon

We determine the exact complexity of classifying compact metric spaces up to homeomorphism. More precisely, the homeomorphism relation on compact metric spaces is Borel bi-reducible with the complete orbit equivalence relation of Polish…

Logic · Mathematics 2014-09-22 Joseph Zielinski

Given a Boolean algebra $A$, we construct another Boolean algebra $B$ with no uncountable well-ordered chains such that the Banach space of real valued continuous functions $C(K_A)$ embeds isometrically into $C(K_B)$, where $K_A$ and $K_B$…

Functional Analysis · Mathematics 2015-05-19 Christina Brech , Piotr Koszmider

Two separated realcompact measurable spaces $(X,\mathcal{A})$ and $(Y,\mathcal{B})$ are shown to be isomorphic if and only if the rings $\mathcal{M}(X,\mathcal{A})$ and $\mathcal{M}(Y,\mathcal{B})$ of all real valued measurable functions…

General Topology · Mathematics 2018-11-07 Soumyadip Acharyya , Sudip Kumar Acharyya , Sagarmoy Bag , Joshua Sack

Prompted by a recent question of G. Hjorth as to whether a bounded Urysohn space is indivisible, that is to say has the property that any partition into finitely many pieces has one piece which contains an isometric copy of the space, we…

Combinatorics · Mathematics 2007-05-23 Christian Delhomme , Claude Laflamme , Maurice Pouzet , Norbert Sauer

We give an elementary proof of a compact embedding theorem in abstract Sobolev spaces. The result is first presented in a general context and later specialized to the case of degenerate Sobolev spaces defined with respect to nonnegative…

Analysis of PDEs · Mathematics 2011-11-01 Seng-Kee Chua , Scott Rodney , Richard L. Wheeden

We answer a question of Aharoni by showing that every separable metric space can be Lipschitz 2-embedded into $c_0$ and this result is sharp; this improves earlier estimates of Aharoni, Assouad and Pelant. We use our methods to examine the…

Functional Analysis · Mathematics 2007-08-30 N. J. Kalton , G. Lancien

The Kantorovich-Rubinshtein metric is an $L^1$-like metric on spaces of probability distributions that enjoys several serendipitous properties. It is complete separable if the underlying metric space of points is complete separable, and in…

General Topology · Mathematics 2022-12-23 Jean Goubault-Larrecq

For an index set $\Gamma$ and a cardinal number $\kappa$ the $\Sigma_{\kappa}$-product of real lines $\Sigma_{\kappa}(\mathbb{R}^{\Gamma})$ consist of all elements of $\mathbb{R}^{\Gamma}$ with $<\kappa$ nonzero coordinates. A compact space…

General Topology · Mathematics 2024-07-08 Krzysztof Zakrzewski

We prove that for any separable Banach space $X$, there exists a compact metric space which is homeomorphic to the Cantor space and whose Lipschitz-free space contains a complemented subspace isomorphic to $X$. As a consequence we give an…

Functional Analysis · Mathematics 2015-11-17 Petr Hájek , Gilles Lancien , Eva Pernecká