Let f be a positive definite function on a locally compact abelian group G. In [3] we showed that measurability of 1 on an open neighbourhood of the zero implies measurability of f on G. As a main tool we used a result about the support of f [3, Th. I]. The aim of this note is to simplify the proof
Strictly Positive Definite Functions
β Scribed by Kuei-Fang Chang
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 490 KB
- Volume
- 87
- Category
- Article
- ISSN
- 0021-9045
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β¦ Synopsis
We give a complete characterization of the strictly positive definite functions on the real line. By Bochner's theorem, this is equivalent to proving that if the separated sequence of real numbers [a n ] describes the points of discontinuity of a distribution function, there exists an almost periodic polynomial with the zeros [a n ]. We prove a useful necessary condition that every strictly normalized, positive definite function f satisfies | f (x)| <1 for all x{0. It is a sufficient condition for strictly positive definiteness that if the carrier of a nonzero finite Borel measure on R is not a discrete set, then the Fourier Stieltjes transform +^of + is strictly positive definite.
π SIMILAR VOLUMES
Let G be a locally compact commutative group and let g and h be positive definite functions on G, which are not identically zero. We show that continuity of gh implies the existence of a character y of Gd (the discrete version of G) such that yg and y h are continuous. As corollary we get a special
Radial positive definite functions are of importance both as the characteristic functions of spherically symmetric probability distributions, and as the correlation functions of isotropic random fields. The Euclid's hat function h n (&x&), x # R n , is the self-convolution of an indicator function s