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In this paper, we study Bernstein, Markov and Nikol’skii type inequalities for arbitrary algebraic polynomials with respect to a weighted Lebesgue space, where the contour and weight functions have some singularities on a given contour.
Keyword: In this paper, we study Bernstein, Markov and Nikol’skii type inequalities for arbitrary algebraic polynomials with respect to a weighted Lebesgue space, where the contour and weight functions have some singularities on a given contour
Let φ={φk}k=−∞∞ denote the extended Takenaka–Malmquist system on unit circle T and let σn,φ(f), f∈L1(T), be the Fejér-type operator based on φ, introduced by V. N. Rusak. We give the convergence criteria for σn,φ(f) in Banach space C(T). Also we prove the Voronovskaya-type theorem for σn,φ(f) on class of holomorphic functions representable by Cauchy-type integrals with bounded densities.
Keywords: Holomorphic functions; Takenaka–Malmquist system; Fejér type operator; Blaschke product; Frostman condition
Let Tn be the linear Hadamard convolution operator acting over Hardy space Hq, 1≤q≤∞. We call Tn a best approximation-preserving operator (BAP operator) if Tn(en)=en, where en(z):=zn, and if ∥Tn(f)∥q≤En(f)q for all f∈Hq, where En(f)q is the best approximation by algebraic polynomials of degree a most n−1 in Hq space. We give necessary and sufficient conditions for Tn to be a BAP operator over H∞. We apply this result to establish an exact lower bound for the best approximation of bounded holomorphic functions. In particular, we show that the Landau-type inequality ∣∣fˆn∣∣+c∣∣fˆN∣∣≤En(f)∞, wher ...Более
In this work, we investigate the order of growth of the modulus of an arbitrary algebraic polynomials in the weighted Lebesgue space, where the contour and the weight functions have some singularities. In particular, we obtain new exact estimations for the growth of the modulus of orthogonal polynomials
We continue studying on the Nikol’skii and Bernstein –Walsh type estimations for complex algebraic polynomials in the bounded and unbounded quasidisks on the weighted Bergman space
Dağıstan ŞİMŞEK | Fahreddin ABDULLAYEV | Meerim İmaş Kızı | Ella ABILAYEVA | Burak OĞUL
This paper is an introduction to soft cone metric spaces. We first define the concept of soft cone metric via soft elements and give basic properties of its. Then, we investigate soft convergence in soft cone metric spaces and prove some important fixed point theorems for contractive mappings on soft cone metric spaces.-
Bu makale esnek koni metrik uzaylara bir giriştir. Önce esnek koni metrik uzayları, esnek eleman yardımıyla tanımladık ve onun temel özelliklerini verdik. Sonra esnek koni metrik uzaylarda esnek yakınsaklık kavramını inceledik ve esnek koni metrik uzaylar üzerinde daralma dö ...Более
In this work, we investigate the order of the growth of the modulus of orthogonal polynomials over a contour and also arbitrary algebraic polynomials in regions with corners in a weighted Lebesgue space, where the singularities of contour and the weight functions satisfy some condition.
We study estimation of the modulus of algebraic polynomials in the bounded and unbounded regions with piecewise-quasismooth boundary, having interior and exterior zero angles, in the weighted Lebesgue space.
In the work, we found integral representations for function spaces that are isometric to spaces of entire functions of exponential type, which are necessary for giving examples of equality of approximation characteristics in function spaces isometric to spaces of non-periodic functions. Sufficient conditions are obtained for the nonnegativity of the delta-like kernels used to construct isometric function spaces with various numbers of variables.
In this work, we study Bernstein-Walsh-type estimations for the derivative of an arbitrary algebraic polynomial in regions with piece wise smooth boundary without cusps of the complex plane. Also, estimates are given on the whole complex plane.