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A functional equation from probability theory


Author: John A. Baker
Journal: Proc. Amer. Math. Soc. 121 (1994), 767-773
MSC: Primary 39B22; Secondary 62E10
DOI: https://doi.org/10.1090/S0002-9939-1994-1186127-5
MathSciNet review: 1186127
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Abstract: The functional equation

$\displaystyle f(x) = \prod\limits_{j = 1}^N {{{[f({\beta _j}x)]}^{{\gamma _j}}}}$ ($ (1)$)

has been used by Laha and Lukacs (Aequationes Math. 16 (1977), 259-274) to characterize normal distributions. The aim of the present paper is to study (1) under somewhat different assumptions than those assumed by Laha and Lukacs by using techniques which, in the author's opinion, are simpler than those employed by the afore-mentioned authors. We will prove, for example, that if $ 0 < {\beta _j} < 1$ and $ {\gamma _j} > 0$ for $ 1 \leq j \leq N, \sum {_{j = 1}^N\beta _j^k{\gamma _j} = 1}$, where k is a natural number, $ f:\mathbb{R} \to [0, + \infty )$, (1) holds for $ x \in \mathbb{R}$ and $ {f^{(k)}}(0)$ exists then either $ f \equiv 0$ or there exists a real constant c such that $ f(x) = \exp (c{x^k})$ for all $ x \in \mathbb{R}$.

References [Enhancements On Off] (What's this?)

  • [1] John A. Baker, Functional equations, tempered distributions and Fourier transforms, Trans. Amer. Math. Soc. 315 (1989), 57-68. MR 979965 (90k:39006)
  • [2] W. Jarczyk, A recurrent method of solving iterative functional equations, Uniwersytet Slaski, Katowice, 1991. MR 1135795 (92k:39005)
  • [3] M. Kuczma, B. Choczewski, and R. Ger, Iterative functional equations, Cambridge Univ. Press, London and New York, 1990. MR 1067720 (92f:39002)
  • [4] M. Laczkovich, Non-negative measurable solutions of a difference equation, J. London Math. Soc. (2) 34 (1986), 139-147. MR 859155 (87m:39003)
  • [5] R. G. Laha and E. Lukacs, On a functional equation which occurs in a characterization problem, Aequationes Math. 16 (1977), 259-274. MR 0471023 (57:10765)
  • [6] E. Vincze, Bemerkung zur Charakterisierung der Gauss'schen Fehlergesetzes, Magyar Tud. Acad. Mat. Kutató Int. Kösl. 7 (1962), 357-61. MR 0152773 (27:2748)
  • [7] E. Zeidler, Nonlinear functional analysis and its applications. I, Springer-Verlag, New York, Berlin, Heidelberg, and Tokyo, 1986. MR 816732 (87f:47083)

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Additional Information

DOI: https://doi.org/10.1090/S0002-9939-1994-1186127-5
Keywords: Functional equation, probability
Article copyright: © Copyright 1994 American Mathematical Society

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