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Journal of Zhejiang University (Science Edition)  2023, Vol. 50 Issue (2): 131-136    DOI: 10.3785/j.issn.1008-9497.2023.02.001
Mathematics and Computer Science     
The almost convergence of sequence and measurable function
Xinyu YANG(),Yi LU,Panyan SHI,Lizhen ZHOU()
School of Mathematical Sciences,Soochow University,Suzhou 213000,Jiangsu Province,China
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Abstract  

To generalize the concept of classic limit of sequence, this paper introduces the definition of almost convergent sequence and proves several important properties together with a necessary and sufficient condition of almost convergence, hence building an equivalent relation between almost and strictly convergence. Moreover, based on the Lebesgue measure and by introducing the conception of density of subsets on Rn,we also provide the definition of almost convergence of measurable functions, including some properties and a basic theorem of almost convergence similar to sequence. Then we introduce the definition of almost continuous function. At last, based on the Lebesgue differential theorem, it is proved that any measurable function is almost continuous, almost everywhere on Rn.



Key wordsdensity      almost convergence      almost continuous     
Received: 07 April 2022      Published: 21 March 2023
CLC:  O 174.1  
Corresponding Authors: Lizhen ZHOU     E-mail: meiyang010420@163.com;zhoulizhen@suda.edu.cn
Cite this article:

Xinyu YANG, Yi LU, Panyan SHI, Lizhen ZHOU. The almost convergence of sequence and measurable function. Journal of Zhejiang University (Science Edition), 2023, 50(2): 131-136.

URL:

https://www.zjujournals.com/sci/EN/Y2023/V50/I2/131


数列和可测函数的几乎收敛性

对经典的数列极限进行了推广,通过引入几乎收敛的定义,证明了几个重要性质以及数列几乎收敛的充分必要条件,建立了几乎收敛与严格收敛之间的等价关系。以Rn上的Lebesgue测度为基础,建立了Rn子集的密度概念,引入了可测函数几乎收敛的定义,证明了与数列几乎收敛平行的若干性质,以及函数几乎收敛基本定理。给出了函数几乎连续的定义,利用Lebesgue微分定理,证明了任意可测函数在Rn上几乎处处几乎连续。


关键词: 密度,  几乎收敛,  几乎连续 
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