Valued Graphs and the Representation Theory of Lie Algebras

Quivers (directed graphs), species (a generalization of quivers) and their representations play a key role in many areas of mathematics including combinatorics, geometry, and algebra. Their importance is especially apparent in their applications to the representation theory of associative algebras,...

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Main Author: Joel Lemay
Format: Article
Language:English
Published: MDPI AG 2012-07-01
Series:Axioms
Subjects:
Online Access:http://www.mdpi.com/2075-1680/1/2/111
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author Joel Lemay
author_facet Joel Lemay
author_sort Joel Lemay
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description Quivers (directed graphs), species (a generalization of quivers) and their representations play a key role in many areas of mathematics including combinatorics, geometry, and algebra. Their importance is especially apparent in their applications to the representation theory of associative algebras, Lie algebras, and quantum groups. In this paper, we discuss the most important results in the representation theory of species, such as Dlab and Ringel’s extension of Gabriel’s theorem, which classifies all species of finite and tame representation type. We also explain the link between species and K-species (where K is a field). Namely, we show that the category of K -species can be viewed as a subcategory of the category of species. Furthermore, we prove two results about the structure of the tensor ring of a species containing no oriented cycles. Specifically, we prove that two such species have isomorphic tensor rings if and only if they are isomorphic as “crushed” species, and we show that if K is a perfect field, then the tensor algebra of a K -species tensored with the algebraic closure of K is isomorphic to, or Morita equivalent to, the path algebra of a quiver.
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spelling doaj.art-374cd7cf3769441fb8dfa40206203da82022-12-22T00:12:31ZengMDPI AGAxioms2075-16802012-07-011211114810.3390/axioms1020111Valued Graphs and the Representation Theory of Lie AlgebrasJoel LemayQuivers (directed graphs), species (a generalization of quivers) and their representations play a key role in many areas of mathematics including combinatorics, geometry, and algebra. Their importance is especially apparent in their applications to the representation theory of associative algebras, Lie algebras, and quantum groups. In this paper, we discuss the most important results in the representation theory of species, such as Dlab and Ringel’s extension of Gabriel’s theorem, which classifies all species of finite and tame representation type. We also explain the link between species and K-species (where K is a field). Namely, we show that the category of K -species can be viewed as a subcategory of the category of species. Furthermore, we prove two results about the structure of the tensor ring of a species containing no oriented cycles. Specifically, we prove that two such species have isomorphic tensor rings if and only if they are isomorphic as “crushed” species, and we show that if K is a perfect field, then the tensor algebra of a K -species tensored with the algebraic closure of K is isomorphic to, or Morita equivalent to, the path algebra of a quiver.http://www.mdpi.com/2075-1680/1/2/111quiverspecieslie algebrarepresentation theoryroot systemvalued graphmodulated quivertensor algebrapath algebraRingel–Hall algebra
spellingShingle Joel Lemay
Valued Graphs and the Representation Theory of Lie Algebras
Axioms
quiver
species
lie algebra
representation theory
root system
valued graph
modulated quiver
tensor algebra
path algebra
Ringel–Hall algebra
title Valued Graphs and the Representation Theory of Lie Algebras
title_full Valued Graphs and the Representation Theory of Lie Algebras
title_fullStr Valued Graphs and the Representation Theory of Lie Algebras
title_full_unstemmed Valued Graphs and the Representation Theory of Lie Algebras
title_short Valued Graphs and the Representation Theory of Lie Algebras
title_sort valued graphs and the representation theory of lie algebras
topic quiver
species
lie algebra
representation theory
root system
valued graph
modulated quiver
tensor algebra
path algebra
Ringel–Hall algebra
url http://www.mdpi.com/2075-1680/1/2/111
work_keys_str_mv AT joellemay valuedgraphsandtherepresentationtheoryofliealgebras