G可积函数的Lebesgue可测性

Botsko在连续和可导的知识基础上推广了Riemann积分,得到了一种新的积分,称为G积分．G积分既不同于Riemann积分也不同于Lebesgue积分．本文通过对G积分的研究,得到了G可积函数一定Lebesgue可测,从而有界G可积函数一定Lebesgue可积;同时我们还证明了这两个积分值相等．     

Lebesgue积分的另一种定义

用可数分法代替有限分法,可去掉函数有界和定义域测度有限的限制,一次性地作出函数Lebesgue可积的定义并得出可积的充要条件.     

两集合并集可测和原集合自身可测的关系

两个Lebesgue可测集(以下简称可测集)的并集是可测集.但是在已知两个集合的并集是可测集的条件下,并不能反推出原集合自身均为可测集.进一步研究两个集合的并集的可测性与原集合自身的可测性之间的联系,得到两个集合自身均可测的一种等价刻画.     

Lebesgue积分列的等度绝对连续性

给出了Lebesgue积分列的等度绝对连续的一个充分必要条件.     

多元Riemann可积函数的特征与完备化

给出了多元Riemann可积函数的基本特征,证明了多元Riemann可积函数空间的完备化是Lebesgue积分空间.     

用泛函观点看LEBESGUE积分

从泛函分析观点来看Lebesgue积分,使得Lebesgue积分可以用泛函分析最简单最基本的方法独立导出．基本做法是将Riemann对于区间[0,1]上的连续函数的积分看成连续函数空间C[0,1]上的连续线性泛函,再将它“自然”延拓到C[0,1]在积分范数意义下的完备化空间,而这个完备化空间正是Lebesgue可积函数空间L1[0,1]．     

Lebesgue积分的产生和意义

论述Lebesgue积分产生的背景和思想形成过程，重点介绍直观、想象、类比、猜测等思维形式在Lebesgue积分产生过程中所发挥的作用．     

关于瑕积分与Lebesgue积分之关系的一种证法

本给出了函数f(x)的瑕积分绝对收敛时．必定Lebesgue可积的一种证明方法．     

关于Lebesgue可积函数的一个推广

f(x)为[0,1]上的Lebesgue可积函数,若它还在0的一个邻域内有界,则f(x^n)(n≥1)也在[0,1]上Lebesgue可积,其积分值的极限当f(x)为单调函数时收敛于f(0 0)。     

求Rp上不变密度的一个直接方法

本文利用一个熟知的多元积分变量变换定理对R^p上的不变密度给出了一个不涉及Haar测度理论的纯微积分处理.对较一般的情形以一个等式的形式给出了非负Lebesgue可测函数为不变密度的充要条件,从而提供了求不变密度的一个直接方法.进一步还对变换群可迁地作用于集的情形导出了所谓严格不变密度的统一的显式表达,并由此证明了严格不变密度的存在性与唯一性.     

Several applications of the theory of random conjugate spaces to measurability problems

The central purpose of this paper is to illustrate that combining the recently developed theory of random conjugate spaces and the deep theory of Banach spaces can, indeed, solve some difficult measurability problems which occur in the recent study of the Lebesgue (or more general, Orlicz)-Bochner function spaces as well as in a slightly different way in the study of the random functional analysis but for which the measurable selection theorems currently available are not applicable. It is important that this paper provides a new method of studying a large class of the measurability problems, namely first converting the measurability problems to the abstract existence problems in the random metric theory and then combining the random metric theory and the relative theory of classical spaces so that the measurability problems can be eventually solved. The new method is based on the deep development of the random metric theory as well as on the subtle combination of the random metric theory with classical space theory.     

关于C-积分的一个注记

本文研究了高维空间中C-积分的有关性质.利用被积函数的可测性质,证明了若函数在I0上C-可积,则存在I0上的一个部分,使得函数在该部分上Lebesgue可积.推广了文献[6]中的结论.     

Strong solution of Itô type set-valued stochastic differential equation

In this paper, we shall firstly illustrate why we should introduce an It5 type set-valued stochastic differential equation and why we should notice the almost everywhere problem. Secondly we shall give a clear definition of Aumann type Lebesgue integral and prove the measurability of the Lebesgue integral of set-valued stochastic processes with respect to time t. Then we shall present some new properties, especially prove an important inequality of set-valued Lebesgue integrals. Finally we shall prove the existence and the uniqueness of a strong solution to the It5 type set-valued stochastic differential equation.     

Taylor's theorem for a function of several variablesClassroom notes

In this note the measure problem for the Lebesgue measure is discussed in terms of metric space theory. It is illuminated that under the axiom of choice most of the subsets of [0, 1) with positive outer measure are non‐Lebesgue measurable. This fact is adequate to emphasize the significance of Lebesgue measurability as well as the essentiality of the axiom of choice.     

β-变换下攀援集和distal集的测度性质

设β1为实数,T_β为[0,1]的β变换.攀援集的任何两个点随着时间的转移会越来越接近但同时又总能在任意长时间后保持一定的距离.证明了在Lebesgue测度意义下关于T_β的攀援集是一个零测集.Distal点对的两个点表示随着时间的转移始终保持着一定的距离.如果固定其中一个点x_0,所有满足x∈[0,1)且lim inf n→∞|T_β~n(x)-T_β~n(x_0)|0的点称为关于x_0的distal集,如果把这个集合记为R_β(x_0),根据Borel-Cantelli引理得到R_β(x_0)的Lebesgue测度为零.     

On Lebesgue Functions of Uniformly Bounded Orthonormal Systems

A complement to A. M. Olevskii's fundamental inequality on the logarithmic growth of Lebesgue functions of an arbitrary uniformly bounded orthonormal system on a set of positive measure is made. Namely, the index where the Lebesgue functions have growth slightly weaker than logarithmic can be chosen independently of the variable. The theorem proved in this paper improves a result established earlier by the author.     

On the separation of regularity properties of the reals

We present a model where ω ₁ is inaccessible by reals, Silver measurability holds for all sets but Miller and Lebesgue measurability fail for some sets. This contributes to a line of research started by Shelah in the 1980s and more recently continued by Schrittesser and Friedman (see [7]), regarding the separation of different notions of regularity properties of the real line.     

On the Deductive Strength of Various Distributivity Axioms for Boolean Algebras in Set Theory

In this article, we shall show the generalized notions of distributivity of Boolean algebras have essential relations with several axioms and properties of set theory, say the Axiom of Choice, the Axiom of Dependence Choice, the Prime Ideal Theorems, Martin's axioms, Lebesgue measurability and so on.