Some Tauberian theorems for iterations of Hölder integrability method

被引:0
|
作者
Zerrin Önder
İbrahim Çanak
机构
[1] Ege University,Department of Mathematics
来源
Positivity | 2019年 / 23卷
关键词
Divergent integrals; (; , ; ) integrability; Tauberian theorems; Slowly decreasing functions; Slowly oscillating functions; 40E05; 40A10; 40C10;
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摘要
Let f be a real or complex-valued function on [1,∞)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$[1,\infty )$$\end{document} which is continuous over every finite interval [1, x) for 1<x<∞\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1<x<\infty $$\end{document}. We set s(x):=∫1xf(t)dt\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$s(x):=\int _{1}^{x}f(t)dt$$\end{document} and define σk(s(x))\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sigma _{k}(s(x))$$\end{document} by σk(s(x))=1x∫1xσk-1(s(t))dt,k≥1s(x),k=0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\begin{aligned} \sigma _{k}(s(x))=\left\{ \begin{array}{ll} \displaystyle {\frac{1}{x}\int _{1}^{x}} \sigma _{k-1}(s(t))dt,&{}\quad k\ge 1\\ s(x),&{}\quad k=0 \end{array} \right. \end{aligned}$$\end{document}for each nonnegative integer k. An improper integral ∫1∞f(x)dx\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\begin{aligned} \int _{1}^{\infty } f(x)dx \end{aligned}$$\end{document}is said to be integrable to a finite number μ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mu $$\end{document} by the k-th iteration of Hölder or Cesàro mean method of order one, or for short, the (H, k) integrable to μ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mu $$\end{document} if limx→∞σk(s(x))=μ.\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\begin{aligned} \lim _{x\rightarrow \infty }\sigma _{k}(s(x))=\mu . \end{aligned}$$\end{document}In this case, we write s(x)→μ(H,k)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$s(x)\rightarrow \mu \,\,(H,k)$$\end{document}. It is clear that the (H, k) integrability method reduces to the ordinary convergence for k=0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$k=0$$\end{document} and the (H, 1) integrability method is (C, 1) integrability method. It is known that limx→∞s(x)=μ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\lim _{x \rightarrow \infty } s(x) =\mu $$\end{document} implies limx→∞σk(s(x))=μ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\lim _{x \rightarrow \infty }\sigma _{k}(s(x)) =\mu $$\end{document}. But the converse of this implication is not true in general. In this paper, we obtain some Tauberian conditions for the iterations of Hölder integrability method under which the converse implication holds.
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页码:1179 / 1193
页数:14
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