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In mathematics, the Lévy–Prokhorov metric (sometimes known just as the Prokhorov metric) is a metric (i.e., a definition of distance) on the collection of probability measures on a given metric space. It is named after the French mathematician Paul Lévy and the Soviet mathematician Yuri Vasilyevich Prokhorov; Prokhorov introduced it in 1956 as a generalization of the earlier Lévy metric. ==Definition== Let be a metric space with its Borel sigma algebra . Let denote the collection of all probability measures on the measurable space . For a subset , define the ε-neighborhood of by : where is the open ball of radius centered at . The Lévy–Prokhorov metric is defined by setting the distance between two probability measures and to be : For probability measures clearly . Some authors omit one of the two inequalities or choose only open or closed ; either inequality implies the other, and , but restricting to open sets may change the metric so defined (if is not Polish). 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「Lévy–Prokhorov metric」の詳細全文を読む スポンサード リンク
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