Bloom, Walter R.; Ressel, Paul Representations of negative definite functions on polynomial hypergroups. (English) Zbl 0999.43006 Arch. Math. 78, No. 4, 318-328 (2002). For commutative hypergroups there exist a Bochner theorem for bounded positive definite functions as well as a Lévy-Khinchin formula for lower bounded, negative definite functions. In this paper the authors derive corresponding results for functions on polynomial hypergroups without any boundedness conditions. In this case, the representing measure and the Lévy measure \(\mu\), respectively, are positive measures on \(\mathbb{R}\) which is regarded as the space of all semicharacters. These measures are usually not unique. Moreover, algebraic conditions are given for \(\text{supp }\mu\subset \mathbb{R}_+\). Proofs are based on a transfer of the problem from polynomial hypergroups to the semigroup \((\mathbb{Z},+)\). Reviewer: Michael Voit (Tübingen) Cited in 1 Document MSC: 43A62 Harmonic analysis on hypergroups 43A35 Positive definite functions on groups, semigroups, etc. 43A10 Measure algebras on groups, semigroups, etc. 43A55 Summability methods on groups, semigroups, etc. 42C15 General harmonic expansions, frames Keywords:Lévy-Khinchin formula; negative definite functions; polynomial hypergroups PDFBibTeX XMLCite \textit{W. R. Bloom} and \textit{P. Ressel}, Arch. Math. 78, No. 4, 318--328 (2002; Zbl 0999.43006) Full Text: DOI