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Related papers: Approximation by generalized Szasz operators invol…

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Our goal in this paper is to extend the theory of quasi-exactly solvable Schrodinger operators beyond the Lie-algebraic class. Let $\cP_n$ be the space of n-th degree polynomials in one variable. We first analyze "exceptional polynomial…

Exactly Solvable and Integrable Systems · Physics 2013-06-20 David Gomez-Ullate , Niky Kamran , Robert Milson

Our objective in this paper is to introduce and investigate a newly-constructed subclass of normalized analytic and bi-univalent functions by means of the Chebyshev polynomials of the second kind. Upper bounds for the second and third…

Complex Variables · Mathematics 2021-02-18 Feras Yousef , Somaia Alroud , Mohamed Illafe

A new Goodman-Sharma type modification of the Meyer-K\"{o}nig and Zeller operator for approximation of bounded continuous functions on [0,1) is presented. We estimate the approximation error of the proposed operator and prove direct and…

Classical Analysis and ODEs · Mathematics 2025-06-18 Ivan Gadjev , Parvan Parvanov , Rumen Uluchev

The Sz\'asz inequality is a classical result that provides a bound for polynomials with zeros in the upper half of the complex plane, expressed in terms of their low-order coefficients. Generalizations of this result to polynomials in…

Functional Analysis · Mathematics 2025-07-15 Piotr Pikul , Oskar Jakub Szymański , Michał Wojtylak

We prove matching direct and inverse theorems for uniform polynomial approximation with $A^*$ weights (a subclass of doubling weights suitable for approximation in the $L_\infty$ norm) having finitely many zeros and not too "rapidly…

Classical Analysis and ODEs · Mathematics 2015-10-27 Kirill A. Kopotun

We establish the most general Szasz type estimates for homogeneous Besov and Lizorkin-Triebel spaces, and their realizations.

Functional Analysis · Mathematics 2021-05-06 Gérard Bourdaud

In the present paper, we introduce the Chlodowsky variant of (p,q) Kantorovich-Stancu-Schurer operators on the unbounded domain which is a generalization of (p,q) Bernstein-Stancu-Kantorovich operators. We have also derived its Korovkin…

Classical Analysis and ODEs · Mathematics 2016-05-31 Vishnu Narayan Mishra , Shikha Pandey

The classical Szeg\H{o}-Verblunsky theorem relates integrability of the logarithm of the absolutely continuous part of a probability measure on the circle to square summability of the sequence of recurrence coefficients for the orthogonal…

Functional Analysis · Mathematics 2022-02-22 Peter C. Gibson

We apply the geometric approach provided by $\Sigma$-operators to develop a theory of $p$-summability for multilinear operators. In this way, we introduce the notion of Lipschitz $p$-summing multilinear operators and show that it is…

Functional Analysis · Mathematics 2020-04-14 Jorge Carlos Angulo-López , Maite Fernández-Unzueta

We study generalized quasiconformal mappings in the context of the inverse Poletsky inequality. We consider the local behavior and the boundary behavior of mappings with the inverse Poletsky inequality. In particular, we obtain logarithmic…

Complex Variables · Mathematics 2023-06-06 Vladimir Gol'dshtein , Evgeny Sevost'yanov , Alexander Ukhlov

We introduce a class of multidimensional Schr\"odinger operators with elliptic potential which generalize the classical Lam\'e operator to higher dimensions. One natural example is the Calogero--Moser operator, others are related to the…

Quantum Algebra · Mathematics 2009-11-07 Oleg Chalykh , Pavel Etingof , Alexei Oblomkov

It is well known that iterates of quasi-compact operators converge towards a spectral projection, whereas the explicit construction of the limiting operator is in general hard to obtain. Here, we show a simple method to explicitly construct…

Functional Analysis · Mathematics 2017-06-05 Johannes Nagler

In this paper, using generalized k-fractional integral operator (in terms of the Gauss hypergeometric function), we establish new results on generalized k-fractional integral inequalities by considering the extended Chebyshev functional in…

Classical Analysis and ODEs · Mathematics 2016-07-19 Vaijanth L. Chinchane

We use weighted polynomial approximation to prove the existence of a compact set K with non-empty interior and a function f is dense in the space A(K) of all continuous functions on K that are holomorphic in the interior of K, endowed with…

Complex Variables · Mathematics 2025-06-26 Stéphane Charpentier , Konstantinos Maronikolakis

It is a classical result in rational approximation theory that certain non-smooth or singular functions, such as $|x|$ and $x^{1/p}$, can be efficiently approximated using rational functions with root-exponential convergence in terms of…

Numerical Analysis · Mathematics 2025-06-27 Kingsley Yeon , Steven B. Damelin

In this paper, we derive an inverse result for bivariate Kantorovich type sampling series for the space of all continuous functions with upto second order partial derivatives are continuous and bounded on $R^2.$ Further, we prove the rate…

Numerical Analysis · Mathematics 2019-05-30 A. Sathish Kumar , Bajpeyi Shivam

This work represents a first systematic attempt to create a common ground for semi-classical and time-frequency analysis. These two different areas combined together provide interesting outcomes in terms of Schr\"odinger type equations.…

Mathematical Physics · Physics 2018-01-17 Elena Cordero , Maurice de Gosson , Fabio Nicola

We prove matching direct and inverse theorems for (algebraic) polynomial approximation with doubling weights $w$ having finitely many zeros and singularities (i.e., points where $w$ becomes infinite) on an interval and not too ``rapidly…

Classical Analysis and ODEs · Mathematics 2015-07-20 Kirill A. Kopotun

The purpose of this paper is to study the approximation of vector valued mappings defined on a subset of a normed space. We investigate Korovkin-type conditions under which a given sequence of linear operators becomes a so-called…

Functional Analysis · Mathematics 2007-05-23 Lorenzo D'Ambrosio

There are two approaches to projective representation theory of symmetric and alternating groups, which are powerful enough to work for modular representations. One is based on Sergeev duality, which connects projective representation…

Representation Theory · Mathematics 2010-11-03 Alexander Kleshchev , Vladimir Shchigolev