scholarly journals Prime ends in theory of mappings with finite distortion in the plane

Filomat ◽  
2017 ◽  
Vol 31 (5) ◽  
pp. 1349-1366 ◽  
Author(s):  
Denis Kovtonyuk ◽  
Igor Petkov ◽  
Vladimir Ryazanov
Keyword(s):  
Boundary Behavior ◽  
Natural Generalization ◽  
Finite Distortion ◽  
Beltrami Equations ◽  
Lipschitz Mappings ◽  
Prime Ends ◽  
The Given ◽  
Mappings With Finite Distortion ◽  
Homeomorphic Extension ◽  
Effective Conditions

In the present paper, it is studied the boundary behavior of the so-called lower Q-homeomorphisms in the plane that are a natural generalization of the quasiconformal mappings. In particular, it was found a series of effective conditions on the function Q(z) for a homeomorphic extension of the given mappings to the boundary by prime ends. The developed theory is applied to mappings with finite distortion by Iwaniec, also to solutions of the Beltrami equations, as well as to finitely bi-Lipschitz mappings that a far-reaching extension of the known classes of isometric and quasiisometric mappings.

On mappings with finite length distortion on Riemann surfaces

2019 ◽  
Vol 33 ◽  
Author(s):  
Serhii Volkov ◽  
Vladimir Ryazanov
Keyword(s):  
Finite Length ◽  
Riemann Surfaces ◽  
Boundary Behavior ◽  
Main Tool ◽  
Natural Generalization ◽  
Finite Distortion ◽  
Lipschitz Mappings ◽  
Geometric Function ◽  
Mappings With Finite Distortion ◽  
Length Distortion

The present paper is a natural continuation of our previous paper (2017) on the boundary behavior of mappings in the Sobolev classes on Riemann surfaces, where the reader will be able to find the corresponding historic comments and a discussion of many definitions and relevant results. The given paper was devoted to the theory of the boundary behavior of mappings with finite distortion by Iwaniec on Riemannian surfaces first introduced for the plane in the paper of Iwaniec T. and Sverak V. (1993) On mappings with integrable dilatation and then extended to the spatial case in the monograph of Iwaniec T. and Martin G. (2001) devoted to Geometric function theory and non-linear analysis. At the present paper, it is developed the theory of the boundary behavior of the so--called mappings with finite length distortion first introduced in the paper of Martio O., Ryazanov V., Srebro U. and Yakubov~E. (2004) in the spatial case, see also Chapter 8 in their monograph (2009) on Moduli in modern mapping theory. As it was shown in the paper of Kovtonyuk D., Petkov I. and Ryazanov V. (2017) On the boundary behavior of mappings with finite distortion in the plane, such mappings, generally speaking, are not mappings with finite distortion by Iwaniec because their first partial derivatives can be not locally integrable. At the same time, this class is a generalization of the known class of mappings with bounded distortion by Martio--Vaisala from their paper (1988). Moreover, this class contains as a subclass the so-called finitely bi-Lipschitz mappings introduced for the spatial case in the paper of Kovtonyuk D. and Ryazanov V. (2011) On the boundary behavior of generalized quasi-isometries, that in turn are a natural generalization of the well-known classes of bi-Lipschitz mappings as well as isometries and quasi-isometries. In the research of the local and boundary behavior of mappings with finite length distortion in the spatial case, the key fact was that they satisfy some modulus inequalities which was a motivation for the consideration more wide classes of mappings, in particular, the Q-homeomorphisms (2005) and the mappings with finite area distortion (2008). Hence it is natural that under the research of mappings with finite length distortion on Riemann surfaces we start from establishing the corresponding modulus inequalities that are the main tool for us. On this basis, we prove here a series of criteria in terms of dilatations for the continuous and homeomorphic extension to the boundary of the mappings with finite length distortion between domains on arbitrary Riemann surfaces.

On Dirichlet problem for Beltrami equations in finitely connected domains

2021 ◽  
Vol 34 ◽  
pp. 85-99
Author(s):  
Ihor Petkov ◽  
Vladimir Ryazanov
Keyword(s):  
Dirichlet Problem ◽  
Boundary Data ◽  
Boundary Behavior ◽  
Beltrami Equation ◽  
Elliptic Systems ◽  
Beltrami Equations ◽  
Prime Ends ◽  
Wide Circle ◽  
Continuous Boundary ◽  
Homeomorphic Solution

Boundary value problems for the Beltrami equations are due to the famous Riemann dissertation (1851) in the simplest case of analytic functions and to the known works of Hilbert (1904, 1924) and Poincare (1910) for the corresponding Cauchy--Riemann system. Of course, the Dirichlet problem was well studied for uniformly elliptic systems, see, e.g., \cite{Boj} and \cite{Vekua}. Moreover, the corresponding results on the Dirichlet problem for degenerate Beltrami equations in the unit disk can be found in the monograph \cite{GRSY}. In our article \cite{KPR1}, see also \cite{KPR3} and \cite{KPR5}, it was shown that each generalized homeomorphic solution of a Beltrami equation is the so-called lower $Q-$homeomorphism with its dilatation quotient as $Q$ and developed on this basis the theory of the boundary behavior of such solutions. In the next papers \cite{KPR2} and \cite{KPR4}, the latter made possible us to solve the Dirichlet problem with continuous boundary data for a wide circle of degenerate Beltrami equations in finitely connected Jordan domains, see also [\citen{KPR5}--\citen{KPR7}]. Similar problems were also investigated in the case of bounded finitely connected domains in terms of prime ends by Caratheodory in the papers [\citen{KPR9}--\citen{KPR10}] and [\citen{P1}--\citen{P2}]. Finally, in the present paper, we prove a series of effective criteria for the existence of pseudo\-re\-gu\-lar and multi-valued solutions of the Dirichlet problem for the degenerate Beltrami equations in arbitrary bounded finitely connected domains in terms of prime ends by Caratheodory.

On nonhomeomorphic mappings with the inverse Poletsky inequality

2020 ◽  
Vol 17 (3) ◽  
pp. 414-436
Author(s):  
Evgeny Sevost'yanov ◽  
Serhii Skvortsov ◽  
Oleksandr Dovhopiatyi
Keyword(s):  
Boundary Behavior ◽  
Hölder Continuity ◽  
Continuous Extension ◽  
Quasiconformal Mappings ◽  
Holder Continuity ◽  
Hölder Continuous ◽  
Finite Distortion ◽  
Mappings Of Finite Distortion ◽  
Lipschitz Continuous ◽  
Inverse Inequality

As known, the modulus method is one of the most powerful research tools in the theory of mappings. Distortion of modulus has an important role in the study of conformal and quasiconformal mappings, mappings with bounded and finite distortion, mappings with finite length distortion, etc. In particular, an important fact is the lower distortion of the modulus under mappings. Such relations are called inverse Poletsky inequalities and are one of the main objects of our study. The use of these inequalities is fully justified by the fact that the inverse inequality of Poletsky is a direct (upper) inequality for the inverse mappings, if there exist. If the mapping has a bounded distortion, then the corresponding majorant in inverse Poletsky inequality is equal to the product of the maximum multiplicity of the mapping on its dilatation. For more general classes of mappings, a similar majorant is equal to the sum of the values of outer dilatations over all preimages of the fixed point. It the class of quasiconformal mappings there is no significance between the inverse and direct inequalities of Poletsky, since the upper distortion of the modulus implies the corresponding below distortion and vice versa. The situation significantly changes for mappings with unbounded characteristics, for which the corresponding fact does not hold. The most important case investigated in this paper refers to the situation when the mappings have an unbounded dilatation. The article investigates the local and boundary behavior of mappings with branching that satisfy the inverse inequality of Poletsky with some integrable majorant. It is proved that mappings of this type are logarithmically Holder continuous at each inner point of the domain. Note that the Holder continuity is slightly weaker than the classical Holder continuity, which holds for quasiconformal mappings. Simple examples show that mappings of finite distortion are not Lipschitz continuous even under bounded dilatation. Another subject of research of the article is boundary behavior of mappings. In particular, a continuous extension of the mappings with the inverse Poletsky inequality is obtained. In addition, we obtained the conditions under which the families of these mappings are equicontinuous inside and at the boundary of the domain. Several cases are considered: when the preimage of a fixed continuum under mappings is separated from the boundary, and when the mappings satisfy normalization conditions. The text contains a significant number of examples that demonstrate the novelty and content of the results. In particular, examples of mappings with branching that satisfy the inverse Poletsky inequality, have unbounded characteristics, and for which the statements of the basic theorems are satisfied, are given.

On the boundary behavior of solutions of the Beltrami equations

2012 ◽  
Vol 63 (8) ◽  
pp. 1241-1255 ◽  
Author(s):  
D. A. Kovtonyuk ◽  
I. V. Petkov ◽  
V. I. Ryazanov
Keyword(s):  
Boundary Behavior ◽  
Beltrami Equations

scholarly journals On connection of finite distortion mappings with length distortion in $\mathbb{R}^n$

2021 ◽  
Vol 17 ◽  
pp. 112
Author(s):  
Ye.A. Sevostianov
Keyword(s):  
Finite Length ◽  
Measure Zero ◽  
Finite Distortion ◽  
Mappings With Finite Distortion ◽  
Length Distortion

The present paper is devoted to the investigations of mappings with finite distortion in $\mathbb{R}^n$, $n \geqslant 2$. In the work it is proved that every open discrete mapping with finite distortion by Iwaniec such that the branch set of $f$ is of measure zero is a mapping with finite length distortion provided that the corresponding outer dilatation satisfies the inequality $K_O (x, f) \leqslant K(x)$ a.e., where $K(x) \in L_{loc}^{n-1}(D)$.

scholarly journals On removal of isolates singularities of open discrete mappings

2021 ◽  
Vol 15 ◽  
pp. 124
Author(s):  
Ye.A. Sevostianov
Keyword(s):  
Isolated Singularities ◽  
Finite Distortion ◽  
Mappings With Finite Distortion

We study mappings with finite distortion in $\mathbb{R}^n$, $n \geqslant 2$. For the classes of mappings with branching that satisfy modal inequalities we obtain the set of theorems on removal of isolated singularities.

scholarly journals Markov – Stieltjes transformation of measures and some of its applications

2019 ◽  
Vol 54 (4) ◽  
pp. 468-479
Author(s):  
I. S. Kovalyova
Keyword(s):  
Inversion Formula ◽  
Information Transfer ◽  
Boundary Behavior ◽  
Integral Operators ◽  
Point Of View ◽  
Stieltjes Transform ◽  
Theory Of Information ◽  
The Given ◽  
The Uniqueness Theorem ◽  
Stieltjes Type

The paper is devoted to the study of the properties of the Markov – Stieltjes transformation of measures. In the works of J. Anderson, A. A. Pekarsky, N. S. Vyacheslavov, E. P. Mochalina et al., the functions of Markov – Stieltjes type were studied from the point of view of the approximation theory. In the works of A.R. Mirotin and the author, the Markov – Stieltjes transform of functions was studied as an operator in Hardy and Lebesgue spaces. In this paper, the general properties of the Markov – Stieltjes transform of measures are studied, the theorem of analyticity and the uniqueness theorem are proved, the Markov – Stieltjes transformations of positive and complex measures are described, the inversion formula and the continuity theorem are established, the boundary behavior of the given transformation is investigated. In particular, the analogues of the Sokhotsky – Plemelya formulas are established. Applications to the theory of self-conjugate operators are given. In addition, the results obtained can find use in the theory of functions and integral operators, as well as in the theory of information transfer, in particular, in the theory of signal processing.

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