Abstract
Turán’s problem is to determine the greatest possible value of the integral ∫ℝ df(x)dx/ f (0) for positive definite functions f (x), x ∈ ℝd, supported in a given convex centrally symmetric body D ⊂ ℝd. In this note we consider the 2-dimensional Turán problem for positive definite functions of the form f(x) = φ (∥x∥1), x ∈ ℝ2, with φ supported in [0,π].
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Berdysheva, E.E., Berens, H. Über ein Turánsches Problem für ℓ-1 radiale, positiv definite Funktionen. Results. Math. 47, 17–32 (2005). https://doi.org/10.1007/BF03323009
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DOI: https://doi.org/10.1007/BF03323009