Published online by Cambridge University Press: 24 October 2008
Suppose that k(x) is of bounded variation in (− ∞, ∞) and that s(x) is bounded and continuous in the same range. Let
† Integrals with unspecified limits are over (− ∞, ∞).
† Pitt, H. R., “An extension of Wiener's general Tauberian theorem”, American Journal of Math. 60 (1938), 532–4CrossRefGoogle Scholar. We vise case (A) of the theorem.
‡ A singular function is continuous, of bounded variation and not constant, and has zero derivative almost everywhere.
† Wiener, N. and Pitt, H. R., “On absolutely convergent Fourier-Stieltjes transforms”, Duke Journal, 4 (1938), 420–36CrossRefGoogle Scholar, Theorem 1. When these Mercerian theorems were first proved I hoped that the class V* could be extended to include all functions of bounded variation. However, Theorem 3 of the above paper shows that some condition on the singular component of k(x) is essential, and it seems most natural to suppose that it vanishes altogether.
† See, for example, Bochner, S., Vorlesungen fiber Fouriersche Integrate (Leipzig, 1932)Google Scholar, Satz 18.
† The special case in which k(x) is absolutely continuous except at 0 has been treated by Paley, and Wiener, , “Fourier transforms in the complex domain”, American Math. Soc. Colloquium Publications, vol. 19 (New York, 1934)Google Scholar, Theorem XVII.
† Hausdorff, F., “Summationsmethoden und Momentfolgen”, Math. Zeitschrift, 37 (1921), 74–109.CrossRefGoogle Scholar
‡ Pitt, H. R., “General Tauberian theorems”, Proc. London Math. Soc. (2), 44 (1938), 243–88CrossRefGoogle Scholar, § 4·3.
§ See, for example, Bieberbach, L., Lehrbuch der Funktionentheorie (Springer, 1931), p. 138.Google Scholar
† Mercer, J., Proc. London Math. Soc. (2), 5 (1907), 206–24.CrossRefGoogle Scholar
† See Pitt, H. R., “General Tauberian theorems”, Proc. London Math. Soc. (2), 44 (1938), 243–88CrossRefGoogle Scholar, § 2. The particular form of Tauberian theorem for Borel summation which we use below is contained in Theorem 16 of the same paper.