Ditkin set

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In mathematics, a Ditkin set, introduced by (Ditkin 1939), is a closed subset of the circle such that a function f vanishing on the set can be approximated by functions φnf with φ vanishing in a neighborhood of the set.


  • Ditkin, V. (1939), "On the structure of ideals in certain normed rings", Uchenye Zapiski Moskov. Gos. Univ. Matematika, 30: 83–130, MR 0002012