Semigroup compactifications by generalized distal functions and a fixed point theorem

The notion of Semigroup compactification which is in a sense, a generalization of the classical Bohr (almost periodic) compactification of the usual additive reals R, has been studied by J. F. Berglund et. al. [2]. Their approach to the theory of semigroup compactification is based on the Gelfand-Na...

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Main Author: R. D. Pandian
Format: Article
Language:English
Published: Wiley 1991-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Online Access:http://dx.doi.org/10.1155/S0161171291000285
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author R. D. Pandian
author_facet R. D. Pandian
author_sort R. D. Pandian
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description The notion of Semigroup compactification which is in a sense, a generalization of the classical Bohr (almost periodic) compactification of the usual additive reals R, has been studied by J. F. Berglund et. al. [2]. Their approach to the theory of semigroup compactification is based on the Gelfand-Naimark theory of commutative C* algebras, where the spectra of admissible C*-algebras, are the semigroup compactifications. H. D. Junghenn's extensive study of distal functions is from the point of view of semigroup compactifications [5]. In this paper, extending Junghenn's work, we generalize the notion of distal flows and distal functions on an arbitrary semitopological semigroup S, and show that these function spaces are admissible C*- subalgebras of C(S). We then characterize their spectra (semigroup compactifications) in terms of the universal mapping properties these compactifications enjoy. In our work, as it is in Junghenn's, the Ellis semigroup plays an important role. Also, relating the existence of left invariant means on these algebras to the existence of fixed points of certain affine flows, we prove the related fixed point theorem.
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spelling doaj-art-293846f53477436da6fbd517e2cf39db2025-08-20T02:03:54ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04251991-01-0114225326010.1155/S0161171291000285Semigroup compactifications by generalized distal functions and a fixed point theoremR. D. Pandian0Department of Mathematics, North Central College, Naperville 60566, IL, USAThe notion of Semigroup compactification which is in a sense, a generalization of the classical Bohr (almost periodic) compactification of the usual additive reals R, has been studied by J. F. Berglund et. al. [2]. Their approach to the theory of semigroup compactification is based on the Gelfand-Naimark theory of commutative C* algebras, where the spectra of admissible C*-algebras, are the semigroup compactifications. H. D. Junghenn's extensive study of distal functions is from the point of view of semigroup compactifications [5]. In this paper, extending Junghenn's work, we generalize the notion of distal flows and distal functions on an arbitrary semitopological semigroup S, and show that these function spaces are admissible C*- subalgebras of C(S). We then characterize their spectra (semigroup compactifications) in terms of the universal mapping properties these compactifications enjoy. In our work, as it is in Junghenn's, the Ellis semigroup plays an important role. Also, relating the existence of left invariant means on these algebras to the existence of fixed points of certain affine flows, we prove the related fixed point theorem.http://dx.doi.org/10.1155/S0161171291000285
spellingShingle R. D. Pandian
Semigroup compactifications by generalized distal functions and a fixed point theorem
International Journal of Mathematics and Mathematical Sciences
title Semigroup compactifications by generalized distal functions and a fixed point theorem
title_full Semigroup compactifications by generalized distal functions and a fixed point theorem
title_fullStr Semigroup compactifications by generalized distal functions and a fixed point theorem
title_full_unstemmed Semigroup compactifications by generalized distal functions and a fixed point theorem
title_short Semigroup compactifications by generalized distal functions and a fixed point theorem
title_sort semigroup compactifications by generalized distal functions and a fixed point theorem
url http://dx.doi.org/10.1155/S0161171291000285
work_keys_str_mv AT rdpandian semigroupcompactificationsbygeneralizeddistalfunctionsandafixedpointtheorem