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In mathematics, the Hahn–Kolmogorov theorem characterizes when a finitely additive function with non-negative (possibly infinite) values can be extended to a ''bona fide'' measure. It is named after the Austrian mathematician Hans Hahn and the Russian/Soviet mathematician Andrey Kolmogorov. ==Statement of the theorem== Let be an algebra of subsets of a set Consider a function : which is ''finitely additive'', meaning that : for any positive integer ''N'' and disjoint sets in . Assume that this function satisfies the stronger ''sigma additivity'' assumption : for any disjoint family of elements of such that . (Functions obeying these two properties are known as pre-measures.) Then, extends to a measure defined on the sigma-algebra generated by ; i.e., there exists a measure : such that its restriction to coincides with If is -finite, then the extension is unique. 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「Hahn–Kolmogorov theorem」の詳細全文を読む スポンサード リンク
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