Английская Википедия:Denjoy–Luzin theorem
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In mathematics, the Denjoy–Luzin theorem, introduced independently by Шаблон:Harvs and Шаблон:Harvs states that if a trigonometric series converges absolutely on a set of positive measure, then the sum of its coefficients converges absolutely, and in particular the trigonometric series converges absolutely everywhere.
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