Submitted:
24 November 2025
Posted:
25 November 2025
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Abstract
In this paper, we study the behavior of the m − th derivatives of general algebraic polynomials in weighted Bergman spaces defined in domains of the complex plane bounded by piecewise smooth curves with nonzero exterior angles and zero interior angles. Our approach involves establishing upper bounds on the growth of these derivatives not only interior of the unbounded domain but also on the closure of given domain. Through this analysis, we reveal detailed patterns in the growth of the m − th derivatives of algebraic polynomials throughout the complex plane, depending on the properties of the weighted function and the domain.
Keywords:
algebraic polynomial
; quasiconformal mapping
; smooth curve
; Bernstein–Walsh–Markov inequality
; polynomial estimates
1. Introduction and Preliminaries
Let denote the complex plane, be a bounded Jordan region (without loss of generality, we will assume that and ; . For and we set: . Let be the univalent conformal mapping of onto such that and ; . For let denote the exterior level curve of L, denote the inner region of , and denote the outer region of .
Let us denote by
the set of all complex-coefficient algebraic polynomials of degree at most n, where .
The distance from a point to a set , denoted by , is defined as
Let be a fixed sequence of distinct points ordered in the positive direction along L, without loss of generality. Let be a fixed constant such that . Assume that the parameters satisfy for all . Let be a measurable function satisfying the inequality for some constant depending only on G and h. Under these assumptions, we define the generalized Jacobi weight function by
Let denote the two-dimensional Lebesgue measure. Given an arbitrary Jordan domain G and a real number , we present:
and, when is rectifiable:
For any the Bernstein-Walsh Lemma [49] states that the following inequality holds:
Assuming is defined by parameters for as specified in (1), the weighted version of inequality (5) follows from [12]:
In order to recall an estimate analogous to (5) for the space , we begin by introducing the following definition.
Definition 1.
[37] (see also [45]) The Jordan curve (or arc) L is called quasiconformal (), if there is a quasiconformal mapping f of the region such that is a circle (or line segment).
Let denote the set of all sense preserving plane homeomorphisms f of the region such that is a circle (a line segment) and let
where is the maximal dilatation of Then L is a quasiconformal curve, if and L is a quasiconformal curve, if
A curve L is called a quasiconformal, if it is a quasiconformal for some
An analogue of the estimates (4) and (6) for regions bounded by quasiconformal curve with the weight function defined as in (1) for all was found in [8] (see, also [6]) and has the following form:
where and are constants independent of n and As shown in previous studies, not all quasiconformal curves are rectifiable (cf. [25,37]).
In [9], an analogous estimate was studied for the –norm, for an arbitrary Jordan region and it was obtained that, for any and arbitrary , the following estimate
is true, where as and c is an asymptotically sharp constant.
In [46] the case was considered where the norm on the right-hand side (4) is replaced by which leads to new version of the Bernstein-Walsh lemma as follows: If the curve is quasiconformal and rectifiable, then there exists a constant depending only onsuch that
holds for every
On the other hand, using the mean value theorem, for an arbitrary Jordan region G, any polynomial and any , we can find that:
In particular, estimates of the form (9) for orthonormal polynomials , over a region and a specific weight function h, were investigated in [1,2,33,47] and others. Similar estimates to (9) were studied, estimates in the space were obtained for any point in the following form:
where and are constants independent of z and depending on the properties of the region G and the behaviour of the weight function Combining (8) and (9), we obtain an estimation on the growth of in .
Thus, as can be seen from (8) and (9), to study the behavior of the derivatives of polynomials in whole it is also necessary to know the behavior of these derivatives at the points of This means that we need to show that the whole plane can be represented as the union of a finite closed region and its complement–an infinite region–(for example, ) and then study the behaviour of in each of these regions separately. Based on this idea, we can break down into for some and investigate the behaviour of in each of the specified regions of and .
In the present study, we extend previous investigations on the problem of obtaining pointwise estimates for higher order derivatives of modulus of within certain unbounded regions characterized by interior zero and exterior non-zero angles. Our goal is to derive estimates in the following form:
where as , depends on the properties of G and h. Analogous results of the (10)-type for some norms and different unbounded regions were obtained by N.A. Lebedev, P.M. Tamrazov and V.K. Dzjadyk (see, for example, [31,32]). Also several studies have addressed the case with various values and region types. For instance, estimates have been obtained for regions with piecewise Dini-smooth boundaries and in [11], for piecewise smooth boundaries without cusps with in [10], for -quasidisks with in [13,15], for regions bounded by asymptotically conformal curves with in [14], for regions with piecewise smooth boundaries featuring interior angles and in [40], and for regions bounded by piecewise asymptotically conformal curves and in [16], among others. For derivatives of order , estimates akin to those in (10) have been explored in various works. Notably, [19] investigates the case , for regions with piecewise smooth boundaries without cusps; [41] considers , for quasidisks under additional functional assumptions; [34] studies , for regions with piecewise smooth boundaries having both zero and nonzero interior angles; [43] addresses , for regions bounded by piecewise Dini-smooth curves with corners; [17] focuses on quasidisks with , ; and [28] studies regions with quasismooth boundaries and similar parameter ranges. These results often rely on a recurrence formula approach, where the estimate for each derivative order is derived from those of lower orders, a method that involves extensive calculations. However, [20] and [29]â”which both consider , for regions bounded by asymptotically conformal curvesâ”as well as our current work, employ a direct method to establish (10)-type estimates, without relying on recursive arguments.
Secondly, to finalize the analysis of the growth of in the entire complex plane, it is necessary to establish an inequality analogous to the Bernstein-Markov-Nikol’skii type within the regions under consideration, as demonstrated below: :
where , is a constant that depends on the properties of G and the weight function h, in general.
The investigation of inequalities of the type (11) began with the foundational works in [26,27] and [48]. Subsequently, similar research has been explored in numerous other studies. Numerous studies have addressed these inequalities for within a range of function spaces, including those by [31,38]-[22,30,39,44] and [35]. Further references can be found in the cited works. A more detailed study on this topic has been made by [3]-[10,15] (for and -quasidisks), [18] (for and -quasidisks), [24] (for and regions with piecewise smooth boundary with interior cusps), [40] (for and regions with piecewise smooth boundaries containing interior angles), [42] (for and regions with piecewise Dini-smooth boundaries having interior zero angles), [43] (for and regions bounded by piecewise Dini-smooth curve with interior nonzero angles) and others.
2. Definitions and Notations
Throughout this paper, are positive constants and are sufficiently small positive constants (generally, they are different in different relations). These constants generally depend on G and inessential parameters for the argument. Otherwise, the dependence will be explicitly stated. For any and the notation means .
Let denote the natural representation of L .
Definition 2.
We say that a Jordan curve or arc L is smoothif has a continuous tangent at every point The class of such smooth curves or arcs is denoted by . Then we write to mean that
According to the "three-point" criterion [23], every piecewise smooth curve (without any cusps) or arc is quasiconformal. Moreover, according to [45], we have the following:
Corollary 1.
If then L is quasiconformal for arbitrary small
We say that a bounded Jordan curve (or arc) is locally smooth at the point if there exists a closed subarc containing z such that every open subarc of ℓ containing z is smooth.
In what follows, we introduce a certain category of regions enclosed by a piecewise smooth boundary curve, where the connecting arcs form interior angles of zero or non-zero exterior angles.
For a Jordan region G with boundary , let denote a finite, ordered set of distinct points placed along L, which, without loss of generality, are assumed to follow the positive orientation. We define each arc as the segment of the boundary connecting the consecutive points and , where the indexing is taken modulo , i.e., .
Definition 3.
[10] We say that a Jordan region if is the union of finitely many smooth arcs connected at points such that L has exterior (with respect to ) angles at the corner points where two arcs and intersect, and L is locally smooth at .
Without loss of generality, we assume that these points on the curve are located in the positive direction such that has exterior angles at the points , and interior zero angles (i.e. interior cusps) at the points .
It is clear from Definition 3, each region may have exterior nonzero angles at the points and interior zero angles () at the the points If then the region G doesn’t have such angles, in this case we will write: ; if then G has only exterior nonzero angles, in this case we will write ; if and then G has only interior zero angles, in this case we will write
Moreover, throughout the paper, we will assume that the points defined in (1) coincide with the points specified in Definition 3.
To simplify the exposition and avoid cumbersome calculations, we will take without loss of generality. After this assumption, we have the region which has exterior nonzero angle at the point and interior zero angle at the point . Note that, the notation "" means that the region G has two exterior nonzero angles at the point
For , let us
Let Without loss of generality, we will assume that For and let us set:
,
, where ; , ,
3. Main Results
We begin by setting up the notational framework required for both the formulation of the main results and the subsequent analysis.
In all theorems and corollaries throughout this section, the weight function is defined by (1) for the case . Also we assume that and , where is specified individually in each result. Now let’s start formulating the new results.
Theorem 1.
Let and for some . Suppose the weight function h is defined by (1) with . Then, for every polynomial , all and , the following estimate holds:
where is a constant independent of n and and
As a consequence, we can consider cases in which the region has either zero or non-zero angles at both points.
Corollary 2.
Let and for some parameters . Then, for every polynomial , all and , we have:
where is a constant independent of n and
Corollary 3.
Let and Then, for every polynomial , all and , have:
where is a constant independent of n and
Now, we can state uniformly estimate of for
Theorem 2.
Let and for some parameter . Then, for every polynomial , all and arbitrarily small , the following estimate holds:
where is a constant, independent of z and the numbers are defined as in (13) and
We can consider separately the cases where the L curve has the same type of angles at both points: exterior nonzero or interior zero angles. In this case, from Theorem 2, we obtain the follows:
Corollary 4.
Under the conditions of Theorem 2, the relation (17) is satisfied for for where
and , are defined as in (13 ).
Corollary 5.
Under the conditions of Theorem 2, the relation (17) is satisfied for for where
and is defined as in (13).
According to (4) (applied to the polynomial ), the estimate (17) and their corollaries (18) and (19) are also valid for with a different constant. Therefore, when the estimate (7) (for the ) is combined with the estimates (2)-(3), the estimate of the growth of in the whole complex plane is obtained. Now, let us present the corresponding statements. Combined Theorem 1 with Theorem 2, we find the following:
Theorem 3.
Let and for some parameter . Then, for every polynomial , all and arbitrarily small , the following estimate holds:
By combining Corollaries 2 and 3 with Corollaries 4 and 5, respectively, we obtain the following:
Corollary 6.
Let and for some parameters . Then, for every polynomial , all and arbitrarily small , the following estimate holds:
4. Some Auxiliary Results
Lemma 1
([1]). Let be a quasiconformal curve, Then
- a)
- The statements and are equivalent. So and are also equivalent.
- b)
-
If thenwhere is a constant, depending on
Corollary 8.
Under the assumptions of Lemma 1, if , then
Corollary 9.
If then
for all
We will also use the following estimate for (see, for example, [21]):
Lemma 2.
Let . Then
i) for any , , ;
ii) for any , ,
Let be a fixed system of distinct points on curve L ordered in the positive direction and the weight function be defined as in (1).
Lemma 3
([11]). Let is a quasiconformal curve Then, for any fixed there exist a level curvesuch that the following holds for anypolynomial ,
5. Proofs
Proof
(Proof of Theorem 1). The proof of Theorems 1 will be carried separating the cases and . Let with , and . For and , let us define
Noting that is analytic in the region and continuous on its closure , also taking account that , we can apply the Cauchy integral representation for unbounded regions to obtain:
Taking the modulus of both parts and considering that for , we obtain:
Therefore,
Let us express the Cauchy derivative formula for within the integral
and taking we find:
Denote by
and estimate these integrals separately.
A) Estimation of Replacing the variable and taking into account (20), we have:
To estimate the integral, for we introduce the following notations:
and perform for the estimates for the specified sets separately:
Applying Lemma 1, Lemma 2 and (20), we obtain the following estimates, respectively:
1.1.
1.1.1. For
1.1.2 For
1.2.
1.2.1. For
1.2.2. For
2.1. Applying (20) and Corollary 9, we get:
and then, combining estimates obtained in cases 1.1-2.1, for all we obtain:
B) Estimation of .
Let us first assume that Replacing the variable , multiplying the integrands numerator and denominator by and using Hölder inequality, we have:
By Lemma 3, we have:
Now, it remains to estimate the following integral:
To estimate this integral, we set:
where is chosen so that and . Taking these notations into account, from (31), we get:
since the points and are isolated. Therefore, we need to estimate for :
Case 1. Let .
1.1. For , we have:
1.2. Let us now . Since and for all and then we get:
For the , we have , then for , we get:
Pnp[ {
. .
+{
]
Pnp{
. where Therefore,
Case 2. Now, let us .
2.1. For , according to Lemma’s 1 and 2, consistently, we get:
2.2. For , we get:
For , , and then, for , we have:
.
+{
.
+[ n2[ 2(q-1)+(q-2)] +1-q+{
] .
+n} 1q
for , and
for , where for
Substituting the last obtained estimates into (24) and taking into account (28), for the case we obtain:
for , and
for . It remains for us to combine the last two inequalities corresponding to the cases and for each
Now, let us consider the case Multiplying the numerator and denominator of the integrand of the inner integral by h in (24), we get:
After replacing the variable and using the Lemmas 1, 2 and according to (20), (26) and (28), we obtain:
According to Lemmas 1, 3 and (20), we find:
Therefore, for any , the proof of Theorem 1 is completed.
In order to finalize the proof, it remains to verify that for all . To this end, we now introduce the notations that will be used in the remainder of the proof. For , let ; For we set: infinite open cover of the curve L; finite open cover of the curve Now, for we have: Next, let Denote by such that and point such that For we have: Then, according to Lemma 1, we obtain: □
Proof
(Proof of Theorem 2). First of all, we present the theorem that we will use, along with its corollaries. Then we prove the estimate for for each .
whereis the constant, independent ofzandand the numbersare defined as in (17) forand in (13), respectively.
whereis defined as in (13).
Now we proceed to the proof of the estimate for , for each and for the region . Let is an arbitrary fixed point; . By the Cauchy integral formula for derivatives, we have:
Then, by applying well-known Bernstein-Walsh inequality (4), we obtain:
If we get:
If , by applying Theorem A and using the Lemmas 1, 2 , for all we get:
Since is arbitrary, we complete the proof of Theorems 2.
The proofs of Corollaries 4 and 5 are obtained in a completely similar way, using Corollaries A and B in (64) in place of Theorem A. □
6. Discussion
We have studied the growth properties of th derivatives of algebraic polynomials in weighted Bergman spaces in bounded and unbounded regions. The regions we have studied are regions whose boundary is a piecewise smooth curve containing zero angles. We have clearly demonstrated the effects of the geometric properties of the region and the behaviour of the wieght function on the growth of the polynomial by considering the zero-angle and non-zero-angle cases together and separately. Initially, we examine the issue within unbounded regions of the complex plane, and subsequently, we derive conclusions regarding the closure of said region. Thereafter, we integrate these findings to procure assessments of the growth behavior of derivatives of algebraic polynomials in the entirety of the complex plane. Consequently, our aim is to make a contribution to the study of polynomial estimation in the weighted Bergman spaces and to establish novel insights regarding the growth characteristics of polynomials.
Author Contributions
Writing and original draft, C.D.G and F.G.A ; Writing and review and editing, C.D.G and F.G.A . All authors have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Data Availability Statement
No data sets were generated or analysed during the current study.
Acknowledgments
The authors would like to thank the referees for their helpful suggestions and comments
Conflicts of Interest
The authors declere no conflicts of interest.
References
- Abdullayev, F.G.; Andrievskii, V.V. : On the orthogonal polynomials in the domains with K-quasiconformal boundary. Izv. Akad. Nauk Az. SSR, Ser. Fiz.-Tekh. Mat. Nauk 1983, 1, 3–7. [Google Scholar]
- Abdullayev, F.G. : Uniform convergence of the generalized Bieberbach polynomials in regions with non zero angles. Acta Math. Hung 1997, 77(3), 223–246. [Google Scholar] [CrossRef]
- Abdullayev, F.G. : On the some properties of the orthogonal polynomials over the region of the complex plane I. Ukr. Math. J. 2000, 52(12), 1807–1817. [Google Scholar] [CrossRef]
- Abdullayev, F.G. : On the some properties of the orthogonal polynomials over the region of the complex plane II. Ukr. Math. J. 2001, 53(1), 1–14. [Google Scholar] [CrossRef]
- Abdullayev, F.G. : On the some properties of the orthogonal polynomials over the region of the complex plane III. Ukr. Math. J. 2001, 53(12), 1934–1978. [Google Scholar] [CrossRef]
- Abdullayev, F.G. : On the interference of the weight boundary contour for orthogonal polynomials over the region. J. Comp. Anal. Appl. 2004, 6(1), 31–42. [Google Scholar]
- Abdullayev, F.G.; Değer, U. : On the orthogonal polynomials with weight having singularities on the boundary of regions in the complex plane. Bull. Belg. Math. Soc. Simon Stevin 2009, 16(2), 235–250. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Aral, D. : On the Bernstein-Walsh type lemmas in regions of the complex plane. Ukr. Math. J. 2011, 63(3), 337–350. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Özkartepe, P. : An analogue of the Bernstein-Walsh lemma in Jordan regions of the complex plane. J. Ineq. Appl. 2013, 570, 7. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Gün, C.D. : On the behavior of the algebraic polynomials in regions with piecewise smooth boundary without cusps. Ann. Pol. Math. 2014, 111, 39–58. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Özkartepe, P. : On the behavior of the algebraic polynomial in unbounded regions with piecewise Dini-smooth boundary. Ukr. Math. J. 2014, 66(5), 645–665. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Özkartepe, P. : On the growth of algebraic polynomials in the whole complex plane. J. Korean Math. Soc. 2015, 52(4), 699–725. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Özkartepe, P. : Uniform and pointwise Bernstein-Walsh-type inequalities on a quasidisk in the complex plane. Bull. Belg. Math. Soc. Simon Stevin 2016, 23(2), 285–310. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Tunç, T. : Uniform and pointwise polynomial inequalities in regions with asymptotically conformal curve on weighted Bergman space. Lobachevskii J. Math. 2017, 38(2), 193–205. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Tunç, T.; Abdullayev, G.A. : Polynomial inequalities in quasidisks on weighted Bergman space. Ukr. Math. J. 2017, 69(5), 675–695. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Abdullayev, G.A.; Şimşek, D. : Bernstein-Walsh-type polynomial inequalities in regions bounded by piecewise asymptotically conformal curve with interior nonzero angles in the Bergman space. Ukr. Math. J. 2019, 71(5), 663–676. [Google Scholar] [CrossRef]
- Abdullayev, F.G. : Bernstein-Walsh-type inequalities for derivatives of algebraic polynomials in quasidiscs. Open Math. 2021, 19, 1847–1876. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Gün, C.D. : Bernstein-Nikolskii-type inequalities for algebraic polynomials in Bergman space in regions of complex plane. Ukr. Math. J. 2021, 73(4), 513–531. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Gün, C.D. : Bernstein-Walsh-type inequalities for derivatives of algebraic polynomials. Bull. Korean Math. Soc. 2022, 59(1), 45–72. [Google Scholar] [CrossRef]
- Abdullayev, F.G.; Imashkyzy, M. : On the behavior of m–th derivatives of polynomials in bounded and unbounded regions without zero angles in weighted Lebesgue spaces. Anal. Math. Phys. 2025, 15(56), 2025 34. [Google Scholar] [CrossRef]
- Andrievskii, V.V.; Belyi, V.I.; Dzyadyk, V.K. Conformal Invariants in Constructive Theorey of Functions of Complex Plane; World Federation Publishers Company: Atlanta, 1995. [Google Scholar]
- Andrievskii, V.V. : Weighted Polynomial Inequalities in the Complex Plane. J. Approx. Theory 2012, 164(9), 1165–1183. [Google Scholar] [CrossRef]
- Ahlfors, L. Lectures on quasiconformal mappings; D. Van Nostrand Company: Princeton, 1966. [Google Scholar]
- Balcı, S.; Imashkyzy, M.; Abdullayev, F.G. : Polynomial inequalities in regions with interior zero angles in the Bergman space. Ukr. Math. J. 2018, 70(3), 362–384. [Google Scholar] [CrossRef]
- Belinskii, P.P. General Properties of Quasiconformal Mappings; (in Russian). Izdat. Nauka Sibirsk. Otdel.: Novosibirsk, 1974. [Google Scholar]
- Bernstein, S.N. : Sur la limitation des derivees des polnomes. C. R. Acad. Sci. Paris. 1930, 190, 338–341. [Google Scholar]
- Bernstein, S.N. : On the best approximation of continuos functions by polynomials of given degree. Izd Akad Nauk SSSR. I, (1952), II (1954) (O nailuchshem problizhenii nepreryvnykh funktsii posredstrvom mnogochlenov dannoi stepeni). Sobraniye sochinenii.I(4), 11–96 (1912)). Izd. Akad. Nauk. SSSR 1952, I(4). [Google Scholar]
- Değer, U.; Abdullayev, F.G. : On the behavior of derivatives of algebraic polynomials in regions with piecewise quasismooth boundary having cusps. Filomat 2024, 38(10), 3467–3492. [Google Scholar] [CrossRef]
- Değer, U.; Imashkyzy, M.; Abdullayev, F.G. : Asymptotic growth of moduli of m-th derivatives of algebraic polynomials in weighted Bergman spaces on regions without zero angles. Axioms 2025, 14(5), 380. [Google Scholar] [CrossRef]
- Ditzian, Z.; Prymak, A. : Nikol’skii inequalities for Lorentz space. Rocky Mt. J. Math. 2010, 40(1), 209–223. [Google Scholar] [CrossRef]
- V.K. Dzyadyk, V.K. Introduction to the Theory of Uniform Approximation of Function by Polynomials; Nauka: Moscow, 1977. [Google Scholar]
- Dzyadyk, V.K.; Shevchuk, I.A. : Theory of Uniform Approximation of Functions by Polynomials. In Chapter 7; Walter de Gruyter: New York, 2008. [Google Scholar]
- Gaier, D. : On the convergence of the Bieberbach polynomials in regions with corners. Const. Approx. 1988, 4, 289–305. [Google Scholar] [CrossRef]
- Gün, C.D. : On some inequalities for derivatives of algebraic polynomials in unbounded regions with angles. Manas J. Eng. 2021, 9(1), 93–103. [Google Scholar] [CrossRef]
- Halan, V.D.; Shevchuk, I.O. : Exact constant in Dzyadyk’s inequality for the derivative of an algebraic polynomial. Ukr. Math. J. 2017, 69(5), 725–733. [Google Scholar] [CrossRef]
- Hille, E.; Szegö, G.; Tamarkin, J.D. : On some generalization of a theorem of A. Markoff. Duke. Math. J. 1937, 3, 729–739. [Google Scholar] [CrossRef]
- Lehto, O.; Virtanen, K.I. Quasiconformal Mappings in the Plane; Springer-Verlag: Berlin, 1973. [Google Scholar]
- Mamedhanov, D.I. : Inequalities of S.M.Nikol’skii type for polynomials in the complex variable on curves. Soviet Math Dokl. 1974, 15, 34–37. [Google Scholar]
- Nikol’skii, S.M. Approximation of Function of Several Variable and Imbeding Theorems; Springer-Verlag: New York, 1975. [Google Scholar]
- Özkartepe, P. : Pointwise Bernstein-Walsh-type inequalities in regions with piecewise Dini-smooth boundary. Manas J. Eng. 2017, 5(3), 35–47. [Google Scholar]
- Özkartepe, P.; Gün, C.D.; Abdullayev, F.G. : Bernstein-Walsh-type inequalities for derivatives of algebraic polynomials on the regions of complex plane. Turk. J. Math. 2022, 46(7), 2572–2609. [Google Scholar] [CrossRef]
- Özkartepe, P. : Inequalities of the Markov-Nikol’skii type in regions with zero interior angles in the Bergman space. Ukr. Math. J. 2023, 75(3), 419–438. [Google Scholar] [CrossRef]
- Özkartepe, P.; Abdullayev, F.G. : On the growth of m-th derivatives of algebraic polynomials in regions with corners in a weighted Bergman space. Proc. Inst. Math. Mech. 2023, 49(1), 109–153. [Google Scholar]
- Pritsker, I. : Comparing norms of polynomials in one and several variables. J. Math. Anal. Appl. 1997, 216, 685–695. [Google Scholar] [CrossRef]
- Rickman, S. : Characterisation of quasiconformal arcs. Ann. Fenn. Math. Series A I. Mathematica 1966, 395, 30. [Google Scholar]
- Stylianopoulos, N. : Strong asymptotics for Bergman polynomials over domains with corners and applications. Const. Approx. 2012, 38(1), 59–100. [Google Scholar] [CrossRef]
- Suetin, P.K. Polynomials Orthogonal over the Region and Bieberbach Polynomials; American Math Soc: Providence, Rhode Island, 1974. [Google Scholar]
- Szegö, G.; Zygmund, A. : On certain mean values of polynomials. J. Anal. Math. 1953, 3(1), 225–244. [Google Scholar] [CrossRef]
- Walsh, J.L. : Interpolation and Approximation by Rational Functions in the Complex Domain. AMS 1960. [Google Scholar]
- Warschawski, S.E. : Über dasrandverhalten der ableitung der abbildungsfunktion bei konformer. Math. Z 1932, 35, 321–456. [Google Scholar] [CrossRef]
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