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Uniform integrability is an important concept in real analysis, functional analysis and measure theory, and plays a vital role in the theory of martingales. The definition used in measure theory is closely related to, but not identical to, the definition typically used in probability. ==Measure theoretic definition== Textbooks on real analysis and measure theory often use the following definition. Let be a positive measure space. A set is called uniformly integrable if to each there corresponds a such that whenever and ==Probability definition== In the theory of probability, the following definition applies. * A class of random variables is called uniformly integrable (UI) if given , there exists such that , where is the indicator function . * An alternative definition involving two clauses may be presented as follows: A class of random variables is called uniformly integrable if: * * There exists a finite such that, for every in , . * * For every there exists such that, for every measurable such that and every in , . The two probabilistic definitions are equivalent. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Uniform integrability」の詳細全文を読む スポンサード リンク
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