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After carrying out an overview on the non Euclidean geometrical setting suitable for the study of Kolmogorov operators with rough coefficients, we list some properties of the functional space $\mathcal{W}$, mirroring the classical $H^1$…

Analysis of PDEs · Mathematics 2023-04-04 Francesca Anceschi , Mirco Piccinini , Annalaura Rebucci

We give direct and inverse theorems for the weighted approximation of functions with endpoint singularities by combinations of Bernstein operators.

Functional Analysis · Mathematics 2010-08-27 Wen-ming Lu , Lin Zhang

Wiener-Hopf plus Hankel operators $W(a)+H(b):L^p(\mathbb{R}^+)\to L^p(\mathbb{R}^+)$ with generating functions $a$ and $b$ from a subalgebra of $L^\infty(\mathbb{R})$ containing almost periodic functions and Fourier images of…

Functional Analysis · Mathematics 2014-10-14 Victor D. Didenko , Bernd Silbermann

In this paper, we study the persistence approximation property for quantitative $K$-theory of filtered $L^p$ operator algebras. Moreover, we define quantitative assembly maps for $L^p$ operator algebras when $p\in [1,\infty)$. Finally, in…

Operator Algebras · Mathematics 2024-12-04 Hang Wang , Yanru Wang , Jianguo Zhang , Dapeng Zhou

In this paper we provide a rigorous mathematical foundation for continuous approximations of a class of systems with piece-wise continuous functions. By using techniques from the theory of differential inclusions, the underlying piece-wise…

Chaotic Dynamics · Physics 2014-08-20 Marius-F. Danca

When an Approximation Theorist looks at well-posed PDE problems or operator equations, and standard solution algorithms like Finite Elements, Rayleigh-Ritz or Trefftz techniques, methods of fundamental or particular solutions and their…

Numerical Analysis · Mathematics 2018-06-20 Robert Schaback

We obtain new equitightness and $C([0,T];L^p(\mathbb{R}^N))$-convergence results for finite-difference approximations of generalized porous medium equations of the form $$ \partial_tu-\mathfrak{L}[\varphi(u)]=g\qquad\text{in…

Analysis of PDEs · Mathematics 2023-02-03 Félix del Teso , Jørgen Endal , Espen R. Jakobsen

Approximations of the image and integral funnel of the closed ball of the space $L_p,$ $p>1,$ under Urysohn type integral operator are considered. The closed ball of the space $L_p,$ $p>1,$ is replaced by the set consisting of a finite…

Functional Analysis · Mathematics 2021-07-20 Anar Huseyin , Nesir Huseyin , Khalik G. Guseinov

We formulate some special conditions for the integrable functions and moduli of continuity. We give the results on rate of approximation of such functions by matrix means of their Fourier series, where the entries of the rows of the matrix…

Classical Analysis and ODEs · Mathematics 2016-08-14 Radosława Kranz , Włodzimierz Łenski , Bogdan Szal

This article establishes the existence of Lyapunov functions for analyzing the stability of a class of state-constrained systems, and it describes algorithms for their numerical computation. The system model consists of a differential…

Optimization and Control · Mathematics 2021-04-14 Marianne Souaiby , Aneel Tanwani , Didier Henrion

Real linear operators emerge in a range of mathematical physics applications. In this paper spectral questions of compact real linear operators are addressed. A Lomonosov-type invariant subspace theorem for antilinear compact operators is…

Spectral Theory · Mathematics 2013-03-28 Santtu Ruotsalainen

The aim of this paper is to establish various factorization results and then to derive estimates for linear functionals through the use of a generalized Taylor theorem. Additionally, several error bounds are established including…

Classical Analysis and ODEs · Mathematics 2024-12-10 Ali Hasan Ali , Zsolt Páles

There are abundant results on Diophantine approximation over fields of positive characteristic (see the survey papers [13, 25]), but there is very little information about simultaneous approximation. In this paper, we develop a technique of…

Number Theory · Mathematics 2017-11-13 Zhiyong Zheng

For a set $\mathbb{W} \subset L_p(\bT^d)$, $1 < p < \infty$, of multivariate periodic functions on the torus $\bT^d$ and a given function $\varphi \in L_p(\bT^d)$, we study the approximation in the $L_p(\bT^d)$-norm of functions $f \in…

Functional Analysis · Mathematics 2013-04-26 Dinh Dung , Charles Micchelli

This paper is in continuation of our work in \cite{PNM}, wherein we introduced generalized Baskakov Kantorovich operators $K_n^a(f;x)$ and established some approximation properties e.g. local approximation, weighted approximation,…

Classical Analysis and ODEs · Mathematics 2015-05-25 Meenu Goyal , P. N. Agrawal

In this paper, the behavior of the sampling Kantorovich operators has been studied, when discontinuous signals are considered in the above sampling series. Moreover, the rate of approximation for the family of the above operators is…

Functional Analysis · Mathematics 2015-08-10 Danilo Costarelli , Anna Maria Minotti , Gianluca Vinti

Given a set of matrices, modeled as samples of a matrix-valued function, we suggest a method to approximate the underline function using a product approximation operator. This operator extends known approximation methods by exploiting the…

Numerical Analysis · Mathematics 2016-11-15 Nira Dyn , Uri Itai , Nir Sharon

In this paper we give a unitary approach for the simultaneous study of the convergence of discrete and integral operators described by means of a family of linear continuous functionals acting on functions defined on locally compact…

Functional Analysis · Mathematics 2017-11-28 Gianluca Vinti , Luca Zampogni

In this paper multivariate extension of the generalized Durrmeyer sampling type series are considered. We establish a Voronovskaja type formula and a quantitative version. Finally some particular examples are discussed.

Functional Analysis · Mathematics 2016-05-25 Carlo Bardaro , Ilaria Mantellini

Approximation theorems, analogous to known results for linear elliptic equations, are obtained for solutions of the heat equation. Via the Cole-Hopf transformation, this gives rise to approximation theorems for a nonlinear parabolic…

Analysis of PDEs · Mathematics 2007-09-25 P. M. Gauthier , N. Tarkhanov