Conjugation in semigroups

The action of any group on itself by conjugation and the corresponding conjugacy relation play an important role in group theory. There have been several attempts to extend the notion of conjugacy to semigroups. In this paper, we present a new definition of conjugacy that can be applied to an arbitr...

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Bibliographic Details
Main Author: Araújo, João (author)
Other Authors: Konieczny, Janusz (author), Malheiro, António (author)
Format: article
Language:eng
Published: 2015
Subjects:
Online Access:http://hdl.handle.net/10400.2/3798
Country:Portugal
Oai:oai:repositorioaberto.uab.pt:10400.2/3798
Description
Summary:The action of any group on itself by conjugation and the corresponding conjugacy relation play an important role in group theory. There have been several attempts to extend the notion of conjugacy to semigroups. In this paper, we present a new definition of conjugacy that can be applied to an arbitrary semigroup and it does not reduce to the universal relation in semigroups with a zero. We compare the new notion of conjugacy with existing definitions, characterize the conjugacy in various semigroups of transformations on a set, and count the number of conjugacy classes in these semigroups when the set is infinite.