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In this paper we prove Korovkin type theorem for iterates of general positive linear operators $T:C\left[ 0,1\right] \rightarrow C\left[ 0,1\right] $ and derive quantitative estimates in terms of modulus of smoothness. In particular, we…

Functional Analysis · Mathematics 2010-12-07 N. I. Mahmudov

By extending the classical quantitative approximation results for positive and linear operators in $L^{p}([0, 1]), 1\le p \le +\infty$ of Berens and DeVore in 1978 and of Swetits and Wood in 1983 to the more general case of sublinear,…

Functional Analysis · Mathematics 2022-12-05 Sorin G. Gal , Constantin P. Niculescu

The classical as well as non commutative Korovkin-type theorems deal with convergence of positive linear maps with respect to modes of convergences such as norm convergence and weak operator convergence. In this article, Korovkin-type…

Functional Analysis · Mathematics 2012-04-10 Kiran Kumar , M. N. N. Namboodiri , Stefano Serra-Capizzano

In this paper we deal with the convergence of sequences of positive linear maps to a (not assumed to be linear) isometry on spaces of continuous functions. We obtain generalizations of known Korovkin-type results and provide several…

Functional Analysis · Mathematics 2019-08-09 M. Hosseini , J. J. Font

This paper is aimed to prove a quantitative estimate (in terms of the modulus of continuity) for the convergence in the nonlinear version of Korovkin's theorem for sequences of weakly nonlinear and monotone operators defined on spaces of…

Functional Analysis · Mathematics 2024-04-18 Sorin G. Gal , Constantin P. Niculescu

The classical Korovkin theorem traditionally relies on the positivity of the underlying sequence of operators. However, in 1968, D. E. Wulbert established the first non-positive version. In this article, we generalize Wulbert's result to…

Functional Analysis · Mathematics 2025-09-19 V. B. Kiran Kumar , M. N. N. Namboodiri , P. C. Vinaya

This survey paper contains a detailed self-contained introduction to Korovkin-type theorems and to some of their applications concerning the approximation of continuous functions as well as of L^p-functions, by means of positive linear…

Classical Analysis and ODEs · Mathematics 2010-09-15 Francesco Altomare

In this paper we prove Korovkin type theorems for sequences of sublinear, monotone and weak additive operators acting on function spaces C(X); where X is a compact or a locally compact metric space. Our results are illustrated by a series…

Functional Analysis · Mathematics 2021-03-08 Sorin G. Gal , Constantin P. Niculescu

This paper establishes an abstract Korovkin-type approximation theorem in general spaces, extending the framework of approximation theory to accommodate broader contexts. A critical result supporting this theorem is the proof that any…

Functional Analysis · Mathematics 2025-09-03 Dilek Söylemez , Mehmet Ünver

This article delves into Korovkin-type theorems in Banach function spaces, as established by Yusuf Zeren et al. (2022). We prove that in this theorem, the positivity of the operators is not a necessary requirement and provide example of a…

Functional Analysis · Mathematics 2024-08-20 V. B. Kiran Kumar , P C Vinaya

We give some Korovkin-type theorems on convergence and estimates of rates of approximations of nets of functions, satisfying suitable axioms, whose particular cases are filter/ideal convergence, almost convergence and triangular…

Functional Analysis · Mathematics 2021-01-15 Antonio Boccuto , Xenofon Dimitriou

We define the associated geometric series for a large class of positive linear operators and study the convergence of the series in the case of sequences of admissible operators. We obtain an inverse Voronovskaya theorem and we apply our…

Classical Analysis and ODEs · Mathematics 2016-08-11 Ulrich Abel , Mircea Ivan , Radu Păltănea

We prove a noncommutative variant of Saskin's classical theorem -- on the connection between Choquet boundaries for function spaces and Korovkin sets -- for operator systems generating separable Type I C*-algebras. The main result implies…

Operator Algebras · Mathematics 2015-05-22 Craig Kleski

In this paper, using the concept of $A$-statistical convergence which is a regular (non-matrix) summability method, we obtain a general Korovkin type approximation theorem which concerns the problem of approximating a function $f$ by means…

Classical Analysis and ODEs · Mathematics 2007-05-23 Esra Erkus , Oktay Duman

For a positive and invertible linear operator $T$ acting on a $C^*$-algebra, we give necessary and sufficient criteria for the inverse operator $T^{-1}$ to be positive, too. Moreover, a simple counterexample shows that $T^{-1}$ need not be…

Operator Algebras · Mathematics 2024-07-09 Jochen Glück , Ulrich Groh

In this article, we analyse the Kantorovich type exponential sampling operators and its linear combination. We derive the Voronovskaya type theorem and its quantitative estimates for these operators in terms of an appropriate K-functional.…

Functional Analysis · Mathematics 2020-02-10 B. Shivam , A. Sathish Kumar

Let $C$ be a closed cone with nonempty interior $C^\circ$ in a Banach space. Let $f:C^\circ \rightarrow C^\circ$ be an order-preserving subhomogeneous function with a fixed point in $C^\circ$. We introduce a condition which guarantees that…

Functional Analysis · Mathematics 2022-08-16 Brian Lins

In the present article, we propose the new class positive linear operators, which discrete type depending on a real parameters. These operators are similar to Jain operators but its approximation properties are different then Jain…

Classical Analysis and ODEs · Mathematics 2019-04-19 Prashantkumar Patel

In this paper we prove analogues of Korovkin's theorem in the context of weakly nonlinear and monotone operators acting on Banach lattices of functions of several variables. Our results concern the convergence almost everywhere, the…

Functional Analysis · Mathematics 2022-06-29 Sorin G. Gal , Constantin P. Niculescu

The present work considers two important convergence techniques, namely deferred type statistical convergence and P-summability method in respect of positive linear operators. With regard to these techniques, we state and prove two general…

Functional Analysis · Mathematics 2021-11-12 Purshottam Narain Agrawal , Rahul Shukla , Behar Baxhaku
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