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A duality theorem for the category of locally compact Hausdorff spaces and continuous maps which generalizes the well-known Duality Theorem of de Vries is proved.

General Topology · Mathematics 2009-05-07 Georgi Dimov

We prove that compact Hausdorff spaces with a $\mathbb{P}$-diagonal are metrizable.

General Topology · Mathematics 2016-09-02 Alan Dow , Klaas Pieter Hart

We give a necessary and sufficient condition for a set of left invariant metrics on a compact Heisenberg manifold to be relatively compact in the corresponding moduli space.

Differential Geometry · Mathematics 2021-03-16 Sebastian Boldt

We establish new criteria for the $R$-badness of a space and apply it to the case of closed surfaces.

Algebraic Topology · Mathematics 2025-11-05 Jaime Benabent Guerrero , Ramón Flores

In a celebrated conjecture D.Sarason stated a necessary and sufficient condition on the symbols f, g in the Bergman space, L^2_a(\Delta) of the unit disk, \Delta, for the products T_{f}T_{\bar g} of associated Toeplitz operators to be…

Complex Variables · Mathematics 2012-11-14 Dieudonne Agbor

For smooth bounded pseudoconvex domains in $mathbb{C}^{2}$, we provide geometric conditions on (the points of infinite type in) the boundary which imply compactness of the $\bar{\partial}$-Neumann operator. It is noteworthy that the proof…

Complex Variables · Mathematics 2007-05-23 Emil J. Straube

We give blow-up analysis for a Brezis and Merle's problem with Dirichlet and Holderian condition. Also, we derive a compactness criterion.

Analysis of PDEs · Mathematics 2018-01-23 Samy Skander Bahoura , Skander Samy

We prove that the Lipschitz free space over a certain type of discrete metric space has the Radon-Nikod\'ym property. We also show that the Lipschitz free space over a complete, locally compact metric space has the Schur or approximation…

Functional Analysis · Mathematics 2021-02-12 Chris Gartland

There is studied problem on solvability of linear non-homogeneous differential equation of higher even order. There is proved the theorem on necessary and sufficient conditions on existence of solutions to the equation in the Schwartz…

Analysis of PDEs · Mathematics 2017-11-28 Valerii Samoilenko , Yuliia Samoilenko

By means of appropriate sparse bounds, we deduce compactness on weighted $L^p(w)$ spaces, $1<p<\infty$, for all Calder\'on-Zygmund operators having compact extensions on $L^2(\mathbb{R}^n)$. Similar methods lead to new results on…

Classical Analysis and ODEs · Mathematics 2024-07-23 Cody B. Stockdale , Paco Villarroya , Brett D. Wick

In this paper, we prove some rigidity theorems for compact Bach-flat $n$-manifold with the positive constant scalar curvature. In particular, our conditions in Theorem 1.4 have the additional properties of being sharp.

Differential Geometry · Mathematics 2017-07-25 Haiping Fu , Jianke Peng

In this paper we show that the compactness of a Loeb space depends on its cardinality, the nonstandard universe it belongs to and the underlying model of set theory we live in. In section 1 we prove that Loeb spaces are compact under…

Logic · Mathematics 2016-09-06 R. Jin , Saharon Shelah

We present a necessary and sufficient condition for the strict positive definiteness of a real, continuous, isotropic and positive definite kernel on a two-point compact homogeneous space. The characterization adds to others previously…

Functional Analysis · Mathematics 2015-10-20 V. S. Barbosa , V. A. Menegatto

We prove a compactness criterion in $L^p({\mu},X)$: a subset of $L^p({\mu},X)$ is relatively norm compact iff the set of integrals of its functions over any measurable set is relatively norm compact, it satisfies the Fr\'echet oscillation…

Functional Analysis · Mathematics 2020-10-29 Youcef Askoura

We give an explicit criterion for a rational lattice in the time-frequency plane to admit a Gabor frame with window in the Schwartz class. The criterion is an inequality formulated in terms of the lattice covolume, the dimension of the…

Functional Analysis · Mathematics 2024-08-08 Ulrik Enstad , Hannes Thiel , Eduard Vilalta

We prove necessary and sufficient conditions for a Calder\'on-Zygmund operator to be compact at the endpoint from $L^{1}(\mathbb R^{d})$ into $L^{1,\infty}(\mathbb R^{d})$.

Classical Analysis and ODEs · Mathematics 2015-12-18 Jan-Fredrik Olsen , Paco Villarroya

The well-known Kolmogorov compactness criterion is extended to the case of variable exponent Lebesgue spaces $L^{p(\cdot)}({\Omega})$, where $\Omega$ is a bounded open set in $\mathbb R^n$ and $p(\cdot)$ satisfies some "standard"…

Functional Analysis · Mathematics 2009-08-07 Humberto Rafeiro

We prove that for a compact metric space the property of having finite covering dimension is equivalent to the existence of a total order with finite snake number.

Metric Geometry · Mathematics 2022-06-14 Ivan Mitrofanov

We prove a T(1) Theorem to completely characterize compactness of Calderon-Zygmund operators. The result provides sufficient and necessary conditions for the compactness of singular integral operators acting on L^p(R).

Classical Analysis and ODEs · Mathematics 2014-10-08 Paco Villarroya

Organising the relevant literature and by letting statistical convergence play the main role in the theory of compactness, a variant of compactness called statistical compactness has been achieved. As in case of sequential compactness, one…

General Topology · Mathematics 2022-01-21 Manoranjan Singha , Ujjal Kumar Hom