Uniform summability of power series

1972 ◽  
Vol 71 (2) ◽  
pp. 335-341 ◽  
Author(s):  
J. C. Kurtz ◽  
W. T. Sledd

AbstractIt is shown that for the Cesàro means (C, α) with α > - 1, and for a certain class of more general Nörlund means, summability of the series σan implies uniform summability of the series σan zn in a Stolz angle at z = 1.If B is a normal matrix and (B) denotes the series summability field with the usual Banach space topology, then the vectors {ek} (ek = {0,0,..., 1,0,...}) are said to form a Toplitz basis for (B) relative to a method H if H — Σakek = a for each a = {ak}ε(B). It is shown for example that the above relation holds for B = (C,α), α> − 1 , and H = Abel method; also for B = (C,α) and H = (C,β) with 0 ≤ α ≤ β.Applications are made to theorems on summability factors.

1994 ◽  
Vol 46 (5) ◽  
pp. 982-994 ◽  
Author(s):  
Rüdiger Kiesel ◽  
Ulrich Stadtmüller

AbstractThe summability fields of generalized Nörlund means (N,p*α,p), α ∈ Ν, are increasing with a and are contained in that of the corresponding power series method (P,p). Particular cases are the Cesàro- and Euler-means with corresponding power series methods of Abel and Borel. In this paper we generalize a convexity theorem, which is well-known for the Cesàro means and which was recently shown for the Euler means to a large class of generalized Nörlund means.


2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Zhichuan Zhu ◽  
Rudong Chen

Two new iterations with Cesàro's means for nonexpansive mappings are proposed and the strong convergence is obtained asn→∞. Our main results extend and improve the corresponding results of Xu (2004), Song and Chen (2007), and Yao et al. (2009).


1994 ◽  
Vol 115 (2) ◽  
pp. 283-290 ◽  
Author(s):  
Pilar Cembranos

A Banach space E is said to have the Banach-Saks property (BS) if every bounded sequence (xn) in E has a subsequence (x′n) with norm convergent Cesaro means; that is, there is x in E such thatIf this occurs for every weakly convergent sequence in E it is said that E has the Weak Banach-Saks property (WBS) (also called Banach-Saks-Rosenthal property).


1981 ◽  
Vol 23 (3) ◽  
pp. 395-412
Author(s):  
R. B. Saxena

Two theorems of T.M. Flett [Quart. J. Math. Oxford Ser. (2) 7 (1956), 81–95] on the degree of approximation to a function by the Cesàro means of its Fourier series are extended to Nörlund means. Their conjugate analogues are also proved.


1934 ◽  
Vol s2-36 (1) ◽  
pp. 516-531 ◽  
Author(s):  
G. H. Hardy ◽  
J. E. Littlewood

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Ferenc Weisz

AbstractWe generalize the classical Lebesgue’s theorem and prove that the $$\ell _1$$ ℓ 1 -Cesàro means of the Fourier series of the multi-dimensional function $$f\in L_1({{\mathbb {T}}}^d)$$ f ∈ L 1 ( T d ) converge to f at each strong $$\omega $$ ω -Lebesgue point.


2013 ◽  
Vol 79 (3-4) ◽  
pp. 545-581
Author(s):  
Laurian Suciu ◽  
Jaroslav Zemánek

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