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We study conjugate-type phenomena for complex-valued harmonic quasiregular mappings in the unit disk across three function space families: $Q(n,p,\alpha)$, $F(p,q,s)$, and the non-derivative $M(p,q,s)$. For a harmonic $K$-quasiregular…

Complex Variables · Mathematics 2026-01-13 Jihua Sun , Junming Liu , Zhi-Gang Wang

We study the quantitative stability of the mapping that to a measure associates its pushforward measure by a fixed (non-smooth) optimal transport map. We exhibit a tight H\"older-behavior for this operation under minimal assumptions. Our…

Optimization and Control · Mathematics 2024-01-08 Guillaume Carlier , Alex Delalande , Quentin Mérigot

We explore the interplay between different definitions of distortion for mappings $f\colon X\to \mathbb{R}^2$, where $X$ is any metric surface, meaning that $X$ is homeomorphic to a domain in $\mathbb{R}^2$ and has locally finite…

Metric Geometry · Mathematics 2024-05-14 Damaris Meier , Kai Rajala

Lower and upper bounds for a given function are important in many mathematical and engineering contexts, where they often serve as a base for both analysis and application. In this short paper, we derive piecewise linear and quadratic…

Optimization and Control · Mathematics 2014-06-17 Gene A. Bunin , Grégory François , Dominique Bonvin

We study on the biholomorphic equivalence of a strongly pseudoconvex bounded domain with differentiable spherical boundary to an open ball, and we study on the biholomorphicity of a proper holomorphic self mapping of a strongly pseudoconvex…

Complex Variables · Mathematics 2007-05-23 Won K. Park

A mapping $f:X\to Y$ between metric spaces is called \emph{little Lipschitz} if the quantity $$ \operatorname{lip}(f(x)=\liminf_{r\to0}\frac{\operatorname{diam} f(B(x,r))}{r} $$ is finite for every $x\in X$. We prove that if a compact (or,…

Classical Analysis and ODEs · Mathematics 2018-02-23 Jan Malý , Ondřej Zindulka

The main purpose of this paper is to investigate the properties of a mapping which is required to be roughly bilipschitz with respect to the Apollonian metric (roughly Apollonian bilipschitz) of its domain. We prove that under these…

Complex Variables · Mathematics 2018-12-18 Yaxiang Li , Matti Vuorinen , Qingshan Zhou

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

We prove continuity on domains up to the boundary for n/2-polyharmonic maps into manifolds. Technically, we show how to adapt Helein's direct approach to the fractional setting. This extends a remark by the author that this is possible in…

Analysis of PDEs · Mathematics 2011-03-29 Armin Schikorra

A homemorphism between domains in $\mathbb R^n$, $n\ge 2$ is quasiconformal, with its intricate analytic and geometric consequences, if the (pointwise) linear dilatation -- a purely metric quantity -- is uniformly bounded. Gehring proved…

Functional Analysis · Mathematics 2026-04-01 Behnam Esmayli , Pekka Koskela , Khanh Nguyen

We prove the following generalization of Schwarz lemma for harmonic mappings. If $u$ is a harmonic mapping of the unit ball $B_n$ onto itself such that $u(0)=0$ and $\|u\|_p:=\left(\int_S|u(\eta)|^pd\sigma(\eta)\right)^{1/p}<\infty$, $p\ge…

Analysis of PDEs · Mathematics 2015-06-23 David Kalaj

In this paper we consider maps on the plane which are similar to quadratic maps in that they are degree 2 branched covers of the plane. In fact, consider for $\alpha$ fixed, maps $f_c$ which have the following form (in polar coordinates):…

Dynamical Systems · Mathematics 2011-07-26 Ben Bielefeld , Scott Sutherland , Folkert Tangerman , J. J. P. Veerman

A natural quantity that measures how well a map $f:\mathbb{R}^{d}\rightarrow \mathbb{R}^{D}$ is approximated by an affine transformation is…

Classical Analysis and ODEs · Mathematics 2015-03-02 Jonas Azzam

Let $q>1$, $(1-\frac{1}{q})a\geq 1$ and let $\Omega\subset \mathbb{R}^2$ be Lipschitz domain. We show that planar mappings in the second order Sobolev space $f\in W^{2,q}(\Omega,\mathbb{R}^2)$ with $|J_f|^{-a}\in L^1(\Omega)$ are…

Analysis of PDEs · Mathematics 2025-07-08 Stanislav Hencl , Kaushik Mohanta

The Hardy space on the unit ball in C^n provides examples of a quasi-free, finite rank Hilbert module which contains a pure submodule isometrically isomorphic to the module itself. For n=1 the submodule has finite codimension. In this note…

Operator Algebras · Mathematics 2007-07-23 Ronald G. Douglas , Jaydeb Sarkar

In this paper, we consider the Cauchy-Riemann equation $\bar\partial u= f$ in a new class of convex domains in $\C^n.$ We prove that under $L^p$ data, we can choose a solution in the Lipschitz space $\Lambda_{\alpha},$ where $\alpha$ is an…

Complex Variables · Mathematics 2007-05-23 Viet-Anh Nguyen , El Hassan Youssfi

Given a compact quantum metric space (A, L), we prove that the domain of L coincides with A if and only if A is finite dimensional. We then show how one can explicitly build many quantum metrics with distinct domains on infinite-dimensional…

Operator Algebras · Mathematics 2026-03-17 Konrad Aguilar , Katrine von Bornemann Hjelmborg , Frederic Latremoliere

New concepts related to approximating a Lipschitz function between Banach spaces by affine functions are introduced. Results which clarify when such approximations are possible are proved and in some cases a complete characterization of the…

Functional Analysis · Mathematics 2007-05-23 Sean M. Bates , William B. Johnson , Joram Lindenstrauss , D. Preiss , Gideon Schechtman

We call the solution of a kind of second order homogeneous partial differential equation as real kernel alpha-harmonic mappings. In this paper, the representation theorem, the Lipschitz continuity, the univalency and the related problems of…

Complex Variables · Mathematics 2024-01-22 Bo-Yong Long , Qi-Han Wang

The paper deals with the interplay between boundedness, order and ring structures in function lattices on the line and related metric spaces. It is shown that the lattice of all Lipschitz functions on a normed space $E$ is isomorphic to its…

Functional Analysis · Mathematics 2019-01-10 Félix Cabello Sánchez , Javier Cabello Sánchez