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On free products of semigroups and a new proof of Isbell's zigzag theorem

On free products of semigroups and a new proof of Isbell's zigzag theorem
On free products of semigroups and a new proof of Isbell's zigzag theorem
J. R. Isbell proved his famous zigzag theorem for semigroups using essentially topological methods in [Epimorphisms and dominions, in "Proceedings of the Conference on Categorical Algebra, La Jolla, 1965," pp. 232–246]. Since then a number of authors have proved this result using a variety of different techniques. We present in this paper a description of the free product of a special amalgam of monoids using the "homological" techniques introduced by the author in [Proc. London Math. Soc. (3)52 (1986), 119–141] and from this derive a short proof of the zigzag theorem. This is the first proof which makes direct use of the amalgamated free product.
amalgam, dominion, free-product, Isbell, monoid, semigroup, zigzag
0021-8693
12-15
Renshaw, James
350100c1-f7c7-44d3-acfb-29b94f21731c
Renshaw, James
350100c1-f7c7-44d3-acfb-29b94f21731c

Renshaw, James (2002) On free products of semigroups and a new proof of Isbell's zigzag theorem. Journal of Algebra, 251 (1), 12-15. (doi:10.1006/jabr.2002.9143).

Record type: Article

Abstract

J. R. Isbell proved his famous zigzag theorem for semigroups using essentially topological methods in [Epimorphisms and dominions, in "Proceedings of the Conference on Categorical Algebra, La Jolla, 1965," pp. 232–246]. Since then a number of authors have proved this result using a variety of different techniques. We present in this paper a description of the free product of a special amalgam of monoids using the "homological" techniques introduced by the author in [Proc. London Math. Soc. (3)52 (1986), 119–141] and from this derive a short proof of the zigzag theorem. This is the first proof which makes direct use of the amalgamated free product.

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More information

Published date: 1 May 2002
Keywords: amalgam, dominion, free-product, Isbell, monoid, semigroup, zigzag

Identifiers

Local EPrints ID: 29858
URI: http://eprints.soton.ac.uk/id/eprint/29858
ISSN: 0021-8693
PURE UUID: e9b7a827-859a-44e9-91d1-6df2430fd452
ORCID for James Renshaw: ORCID iD orcid.org/0000-0002-5571-8007

Catalogue record

Date deposited: 12 May 2006
Last modified: 16 Mar 2024 02:39

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