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In this paper we prove two new abstract compactness criteria in normed spaces. To this end we first introduce the notion of an equinormed set using a suitable family of semi-norms on the given normed space satisfying some natural…

Functional Analysis · Mathematics 2023-06-23 Jacek Gulgowski , Piotr Kasprzak , Piotr Maćkowiak

This paper regroups some of the basic properties of Lipschitz maps and their flows. Many of the results presented here are classical in the case of smooth maps. We prove them here in the Lipschitz case for a better understanding of the…

Classical Analysis and ODEs · Mathematics 2019-01-23 Youness Boutaib

We propose a unifying general (i.e. not assuming the mapping to have any particular structure) view on the theory of regularity and clarify the relationships between the existing primal and dual quantitative sufficient and necessary…

Optimization and Control · Mathematics 2023-06-22 Nguyen Duy Cuong , Alexander Y. Kruger

This article presents a systematic study of a class of maps between quasi-metric spaces that preserve left K-Cauchy sequences. We call such maps left K-Cauchy regular maps. Several characterizations of these maps have been given in terms of…

General Topology · Mathematics 2025-09-30 Om Dev Singh , Anubha Jindal

We show the regularity of, and derive a-priori estimates for (weakly) harmonic maps from a Riemannian manifold into a Euclidean sphere under the assumption that the image avoids some neighborhood of a half-equator. The proofs combine…

Differential Geometry · Mathematics 2009-12-03 Juergen Jost , Yuanlong Xin , Ling Yang

We revisit the phenomenon where, for certain domains $D$, if the squeezing function $s_D$ extends continuously to a point $p\in \partial{D}$ with value $1$, then $\partial{D}$ is strongly pseudoconvex around $p$. In $\mathbb{C}^2$, we…

Complex Variables · Mathematics 2023-02-24 Gautam Bharali

First of all, we prove that open mappings in Orlicz-Sobolev classes $W^{1,\phi}_{\rm loc}$ under the Calderon type condition on $\phi$ have the total differential a.e. that is a generalization of the well-known theorems of…

Complex Variables · Mathematics 2011-01-13 Denis Kovtonyuk , Vladimir Ryazanov , Ruslan Salimov , Evgeny Sevost'yanov

A theorem of A. Ostrowski describing meromorphic functions f such that the family {f(kz):k in C*} is normal, is generalized to holomorphic maps from $C*$ to a projective space.

Complex Variables · Mathematics 2013-12-23 Alexandre Eremenko

We show that the family ${\cal F}_k$ of all meromorphic functions $f$ in a domain $D$ satisfying $$\frac{|f^{(k)}|}{1+|f|}(z)\ge C \qquad \mbox{ for all } z\in D$$ (where $k$ is a natural number and $C>0$) is quasi-normal. The proof relies…

Complex Variables · Mathematics 2017-11-15 Jürgen Grahl , Shahar Nevo

In this paper, we obtain new bounds for the Hausdorff dimension of planar elliptic measure via the application of quasiconformal mappings, with these bounds depending solely on the ellipticity constant of the matrix. In fact, in our case…

Classical Analysis and ODEs · Mathematics 2025-11-04 Ignasi Guillén-Mola

In this article we consider the following generalized quasi-geostrophic equation \partial_t\theta + u\cdot\nabla \theta + \nu \Lambda^\beta \theta =0, \quad u= \Lambda^\alpha \mathcal{R}^\bot\theta, \quad x\in\mathbb{R}^2, where $\nu>0$,…

Analysis of PDEs · Mathematics 2011-08-24 Changxing Miao , Liutang Xue

We prove space-time Schauder estimates $\unicode{x2013}$ optimal regularity estimates in H\"older spaces $\unicode{x2013}$ and well-posedness results for mild and classical solutions of viscous Hamilton$\unicode{x2013}$Jacobi equations with…

Analysis of PDEs · Mathematics 2026-05-29 Espen Robstad Jakobsen , Robin Østern Lien , Artur Rutkowski

We show that a class of quasiregular Latt\`es maps, called orthotopic Latt\`es maps, are cellular Markov maps. This provides examples of expanding Thurston-type maps that are also uniformly quasiregular, and whose visual metrics are…

Dynamical Systems · Mathematics 2025-12-02 Zhiqiang Li , Hanyun Zheng

In this work, we prove three types of results with the strategy that, together, the author believes these should imply the local version of Hilbert's Fifth problem. In a separate development, we construct a nontrivial topology for rings of…

Analysis of PDEs · Mathematics 2012-06-18 Tom McGaffey

The purpose of this paper is to explore conditions which guarantee Lipschitz-continuity of harmonic maps w.r.t. quasihyperbolic metrics. For instance, we prove that harmonic quasiconformal maps are Lipschitz w.r.t. quasihyperbolic metrics.

Complex Variables · Mathematics 2010-04-12 Miodrag Mateljević , Matti Vuorinen

Let M be a monoidal category endowed with a distinguished class of weak equivalences and with appropriately compatible classifying bundles for monoids and comonoids. We define and study homotopy-invariant notions of normality for maps of…

Algebraic Topology · Mathematics 2012-01-04 Emmanuel D. Farjoun , Kathryn Hess

We prove a far-reaching generalization of Rickman's Picard theorem for a surprisingly large class of mappings, based on the recently developed theory of quasiregular values. Our results are new even in the planar case.

Complex Variables · Mathematics 2025-05-16 Ilmari Kangasniemi , Jani Onninen

We prove a couple of results on local continuous extension of proper holomorphic maps $F:D \rightarrow \Omega$, $D, \Omega \varsubsetneq \mathbb{C}^n$, making local assumptions on $\partial{D}$ and $\partial{\Omega}$. The first result…

Complex Variables · Mathematics 2024-04-25 Annapurna Banik

We study dynamics of area-preserving maps in a neighbourhood of an elliptic fixed point. We describe simplified normal forms for a fixed point of co-dimension 3. We also construct normal forms for a generic three-parameter family which…

Dynamical Systems · Mathematics 2018-07-04 Natalia Gelfreikh

It is formulated conditions on functions $Q(x)$ and boundaries of domains under which every $Q$-homeomorphism admits continuous or homeomorphic extension to the boundary in metric spaces with measures.

Complex Variables · Mathematics 2012-10-17 R. Salimov , O. Afanas'eva