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Amalgamation in varieties of algebras

One of the most successful approaches to research in universal algebra has been the study of varieties, initiated by Garett Birkhoff in the 1930's. Examples of varieties include many classes of algebras such as groups, semigroups, lattices and Boolean algebras. In 1927, O. Schreier showed that for a...

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Main Author: Jacobs, David Frank
Other Authors: Brink, Chris H
Format: Thesis
Language:English
Published: Department of Mathematics and Applied Mathematics 2016
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access_status_str Open Access
author Jacobs, David Frank
author2 Brink, Chris H
author_browse Brink, Chris H
Jacobs, David Frank
author_facet Brink, Chris H
Jacobs, David Frank
author_sort Jacobs, David Frank
collection Thesis
description One of the most successful approaches to research in universal algebra has been the study of varieties, initiated by Garett Birkhoff in the 1930's. Examples of varieties include many classes of algebras such as groups, semigroups, lattices and Boolean algebras. In 1927, O. Schreier showed that for any set of extensions of a given group, there is another extension of that group that in some sense contains all other extensions in the set. This property of groups, known as the amalgamation property was generalized to a universal-algebraic setting by R. Fralsse in 1954, and the important question as to which varieties satisfied the amalgamation property arose. While some of the answers to this question were positive (such as for the varieties of lattices, distributive lattices and Boolean algebras), many common varieties such as the variety of semigroups and all non-distributive modular lattice varieties were shown to fail to satisfy the amalgamation property. In the light of these negative results, attempts were made to "localize" this property from the variety to its individual members, the most successful being the notions of amalgamation base and amalgamation class, first introduced by George Gratzer and Henry Lakser in 1971. Investigations into the nature of the amalgamation classes of varieties that fail to satisfy the amalgamation property were carried out in the 1970's and 1980's by among others, Clifford Bergman and Henry Rose, the main focus being congruence distributive varieties, of which lattice varieties form the prime example. The topic of amalgamation has also been studied in fields as diverse as topology, logic and the theory of field extensions. In this dissertation, however, I will focus on the more algebraic results concerning amalgamation. My aim is to present a selection of these results, using as examples varieties of groups, semigroups, lattices and Heyting algebras, in a universal-algebraic framework that is (more or less) self-contained and uniform in its notation. Bibliography: pages 142-150.
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spelling oai:open.uct.ac.za:11427/18368 Amalgamation in varieties of algebras Jacobs, David Frank Brink, Chris H Mathematics One of the most successful approaches to research in universal algebra has been the study of varieties, initiated by Garett Birkhoff in the 1930's. Examples of varieties include many classes of algebras such as groups, semigroups, lattices and Boolean algebras. In 1927, O. Schreier showed that for any set of extensions of a given group, there is another extension of that group that in some sense contains all other extensions in the set. This property of groups, known as the amalgamation property was generalized to a universal-algebraic setting by R. Fralsse in 1954, and the important question as to which varieties satisfied the amalgamation property arose. While some of the answers to this question were positive (such as for the varieties of lattices, distributive lattices and Boolean algebras), many common varieties such as the variety of semigroups and all non-distributive modular lattice varieties were shown to fail to satisfy the amalgamation property. In the light of these negative results, attempts were made to "localize" this property from the variety to its individual members, the most successful being the notions of amalgamation base and amalgamation class, first introduced by George Gratzer and Henry Lakser in 1971. Investigations into the nature of the amalgamation classes of varieties that fail to satisfy the amalgamation property were carried out in the 1970's and 1980's by among others, Clifford Bergman and Henry Rose, the main focus being congruence distributive varieties, of which lattice varieties form the prime example. The topic of amalgamation has also been studied in fields as diverse as topology, logic and the theory of field extensions. In this dissertation, however, I will focus on the more algebraic results concerning amalgamation. My aim is to present a selection of these results, using as examples varieties of groups, semigroups, lattices and Heyting algebras, in a universal-algebraic framework that is (more or less) self-contained and uniform in its notation. Bibliography: pages 142-150. 2016-03-30T07:08:30Z 2016-03-30T07:08:30Z 1995 Master Thesis Masters MSc http://hdl.handle.net/11427/18368 eng application/pdf Department of Mathematics and Applied Mathematics Faculty of Science University of Cape Town
spellingShingle Mathematics
Jacobs, David Frank
Amalgamation in varieties of algebras
thesis_degree_str Master's
title Amalgamation in varieties of algebras
title_full Amalgamation in varieties of algebras
title_fullStr Amalgamation in varieties of algebras
title_full_unstemmed Amalgamation in varieties of algebras
title_short Amalgamation in varieties of algebras
title_sort amalgamation in varieties of algebras
topic Mathematics
url http://hdl.handle.net/11427/18368
work_keys_str_mv AT jacobsdavidfrank amalgamationinvarietiesofalgebras