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Urysohn constructed a separable complete universal metric space homogeneous for all finite subspaces, which is today called the Urysohn universal metric space. Some authors have recently investigated an ultrametric analogue of this space.…

Metric Geometry · Mathematics 2023-06-27 Yoshito Ishiki

This article grew out of the urge to realize explicit examples of solutions for the Ricci flow as families of isometrically embedded submanifolds, together with its Gromov-Hausdorff collapses. To this aim, we consider the Ricci flow of…

Differential Geometry · Mathematics 2021-07-27 Mauro Patrão , Lucas Seco , Llohann D. Sperança

We investigate the relationship between the compactness of embeddings of Sobolev spaces built upon rearrangement-invariant spaces into rearrangement-invariant spaces endowed with $d$-Ahlfors measures under certain restriction on the speed…

Functional Analysis · Mathematics 2022-05-16 Jan Lang , Zdeněk Mihula , Luboš Pick

We prove that each metrizable space (of cardinality less or equal to continuum) has a (first countable) uniform Eberlein compactification and each scattered metrizable space has a scattered hereditarily paracompact compactification. Each…

General Topology · Mathematics 2012-12-19 Taras Banakh , Arkady Leiderman

First, we review local concepts defined previously. A (local) reference frame $\mathrm{F}$ can be defined as an equivalence class of admissible spacetime charts (coordinate systems) having a common domain $\mathrm{U}$ and exchanging by a…

General Relativity and Quantum Cosmology · Physics 2014-12-22 Mayeul Arminjon

The global solutions in critical spaces to the multi-dimensional compressible viscoelastic flows are considered. The global existence of the Cauchy problem with initial data close to an equilibrium state is established in Besov spaces.…

Analysis of PDEs · Mathematics 2010-10-22 Xianpeng Hu , Dehua Wang

We introduce the notion of functionally compact sets into the theory of nonlinear generalized functions in the sense of Colombeau. The motivation behind our construction is to transfer, as far as possible, properties enjoyed by standard…

Functional Analysis · Mathematics 2016-03-01 Paolo Giordano , Michael Kunzinger

We show that every positive expansive flow on a compact metric space consists of a finite number of periodic orbits and fixed points.

Dynamical Systems · Mathematics 2012-11-12 Alfonso Artigue

For every nonempty compact convex subset $K$ of a normed linear space a (unique) point $c_K \in K$, called the generalized Chebyshev center, is distinguished. It is shown that $c_K$ is a common fixed point for the isometry group of the…

Functional Analysis · Mathematics 2012-10-17 Piotr Niemiec

We show that the space of continuous functions over a compact space X admits an equivalent pointwise-lowersemicontinuous locally uniformly rotund norm whenever X admits a fully closed map onto a compact Y such that C(Y) and the spaces of…

Functional Analysis · Mathematics 2023-12-27 Todor Manev

Previously, we have investigated a natural smooth map onto the region surrounded by the graphs of two smooth real-valued functions in the plane converging to a same value or diverges to $+\infty$ or $-\infty$ simultaneously, at each…

General Topology · Mathematics 2026-03-24 Naoki Kitazawa

Inspired by work of Besson-Courtois-Gallot, we construct a flow called the natural flow on a non-positively curved Riemannian manifold $M$. As with the natural map, the $k$-Jacobian of the natural flow is directly related to the critical…

Differential Geometry · Mathematics 2026-03-27 Chris Connell , D. B. McReynolds , Shi Wang

We show that every uniformly recurrent subgroup of a locally compact group is the family of stabilizers of a minimal action on a compact space. More generally, every closed invariant subset of the Chabauty space is the family of stabilizers…

Dynamical Systems · Mathematics 2018-06-04 Nicolás Matte Bon , Todor Tsankov

In this paper we will give a simple proof of a modification of a result on pseudolocality for the Ricci flow by P.Lu without using the pseudolocality theorem 10.1 of Perelman [P1]. We also obtain an extension of a result of Hamilton on the…

Differential Geometry · Mathematics 2010-10-07 Shu-Yu Hsu

In this work we give a detailed description of Matthias G\"unther's proof of the Isometric Embedding Theorem of Riemannian manifolds. Subsequently we will use this method to show that it is possible to construct an isometric embedding of a…

Differential Geometry · Mathematics 2016-07-15 Norman Zergänge

In this paper, we study the behavior of Ricci flows on compact orbifolds with finite singularities. We show that Perelman's pseudolocality theorem also holds on orbifold Ricci flow. Using this property, we obtain a weak compactness theorem…

Differential Geometry · Mathematics 2010-07-12 Bing Wang

The class of subsets of locally convex spaces called $\mu$-compact sets is considered. This class contains all compact sets as well as several noncompact sets widely used in applications. It is shown that many results well known for compact…

Functional Analysis · Mathematics 2015-05-18 V. Yu. Protasov , M. E. Shirokov

We prove a smooth compactness theorem for the space of embedded self-shrinkers in $\RR^3$. Since self-shrinkers model singularities in mean curvature flow, this theorem can be thought of as a compactness result for the space of all…

Differential Geometry · Mathematics 2009-07-16 Tobias H. Colding , William P. Minicozzi

In this article we give sufficient conditions for Komuro expansivity to imply the rescaled expansivity recently introduced by Wen and Wen. Also, we show that a flow on a compact metric space is expansive in the sense of Katok-Hasselblatt if…

Dynamical Systems · Mathematics 2018-01-26 Alfonso Artigue

In this paper, we prove that if a continuous Hamiltonian flow fixes the points in an open subset $U$ of a symplectic manifold $(M,\omega)$, then its associated Hamiltonian is constant at each moment on $U$. As a corollary, we prove that the…

Symplectic Geometry · Mathematics 2008-02-09 Yong-Geun Oh