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Compact Almost Discrete Hypergroups

Published online by Cambridge University Press:  20 November 2018

Michael Voit*
Affiliation:
Mathematisches Institut Technische Universität München Arcisstr.21 80333 München, Germany, e-mail: voit@mathematik.tu-muenchen.de
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Abstract

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A compact hypergroup is called almost discrete if it is homeomorphic to the one-point-compactification of a countably infinite discrete set. If the group Up of all p-adic units acts multiplicatively on the p-adic integers, then the associated compact orbit hypergroup has this property. In this paper we start with an exact projective sequence of finite hypergroups and use successive substitution to construct a new surjective projective system of finite hypergroups whose limit is almost discrete. We prove that all compact almost discrete hypergroups appear in this way—up to isomorphism and up to a technical restriction. We also determine the duals of these hypergroups, and we present some examples coming from partitions of compact totally disconnected groups.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 1997

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