Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms

In this review paper, we treat the topic of fine gradings of Lie algebras. This concept is important not only for investigating the structural properties of the algebras, but, on top of that, the fine gradings are often used as the starting point for studying graded contractions or deformations of t...

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Published in:Symmetry, Integrability and Geometry: Methods and Applications
Date:2008
Main Author: Svobodová, M.
Format: Article
Language:English
Published: Інститут математики НАН України 2008
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/149045
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms / M. Svobodová // Symmetry, Integrability and Geometry: Methods and Applications. — 2008. — Т. 4. — Бібліогр.: 26 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
id nasplib_isofts_kiev_ua-123456789-149045
record_format dspace
spelling Svobodová, M.
2019-02-19T13:16:57Z
2019-02-19T13:16:57Z
2008
Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms / M. Svobodová // Symmetry, Integrability and Geometry: Methods and Applications. — 2008. — Т. 4. — Бібліогр.: 26 назв. — англ.
1815-0659
2000 Mathematics Subject Classification: 17B45; 22E60
https://nasplib.isofts.kiev.ua/handle/123456789/149045
In this review paper, we treat the topic of fine gradings of Lie algebras. This concept is important not only for investigating the structural properties of the algebras, but, on top of that, the fine gradings are often used as the starting point for studying graded contractions or deformations of the algebras. One basic question tackled in the work is the relation between the terms 'grading' and 'group grading'. Although these terms have originally been claimed to coincide for simple Lie algebras, it was revealed later that the proof of this assertion was incorrect. Therefore, the crucial statements about one-to-one correspondence between fine gradings and MAD-groups had to be revised and re-formulated for fine group gradings instead. However, there is still a hypothesis that the terms 'grading' and 'group grading' coincide for simple complex Lie algebras. We use the MAD-groups as the main tool for finding fine group gradings of the complex Lie algebras A₃ = D₃, B₂ = C₂, and D₂. Besides, we develop also other methods for finding the fine (group) gradings. They are useful especially for the real forms of the complex algebras, on which they deliver richer results than the MAD-groups. Systematic use is made of the faithful representations of the three Lie algebras by 4 × 4 matrices: A₃ = sl(4,C), C₂ = sp(4,C), D₂ = o(4,C). The inclusions sl(4,C) É sp(4,C) and sl(4,C) É o(4,C) are important in our presentation, since they allow to employ one of the methods which considerably simplifies the calculations when finding the fine group gradings of the subalgebras sp(4,C) and o(4,C).
This paper is a contribution to the Proceedings of the Seventh International Conference “Symmetry in Nonlinear Mathematical Physics” (June 24–30, 2007, Kyiv, Ukraine). The author acknowledges financial support by NCLF (Nadace ˇ Cesk´y liter´arn´ı fond) and by the grants LC06002 and MSM6840770039 of the Ministry of Education, Youth, and Sports of the Czech Republic
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Інститут математики НАН України
Symmetry, Integrability and Geometry: Methods and Applications
Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms
Article
published earlier
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
title Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms
spellingShingle Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms
Svobodová, M.
title_short Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms
title_full Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms
title_fullStr Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms
title_full_unstemmed Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms
title_sort fine gradings of low-rank complex lie algebras and of their real forms
author Svobodová, M.
author_facet Svobodová, M.
publishDate 2008
language English
container_title Symmetry, Integrability and Geometry: Methods and Applications
publisher Інститут математики НАН України
format Article
description In this review paper, we treat the topic of fine gradings of Lie algebras. This concept is important not only for investigating the structural properties of the algebras, but, on top of that, the fine gradings are often used as the starting point for studying graded contractions or deformations of the algebras. One basic question tackled in the work is the relation between the terms 'grading' and 'group grading'. Although these terms have originally been claimed to coincide for simple Lie algebras, it was revealed later that the proof of this assertion was incorrect. Therefore, the crucial statements about one-to-one correspondence between fine gradings and MAD-groups had to be revised and re-formulated for fine group gradings instead. However, there is still a hypothesis that the terms 'grading' and 'group grading' coincide for simple complex Lie algebras. We use the MAD-groups as the main tool for finding fine group gradings of the complex Lie algebras A₃ = D₃, B₂ = C₂, and D₂. Besides, we develop also other methods for finding the fine (group) gradings. They are useful especially for the real forms of the complex algebras, on which they deliver richer results than the MAD-groups. Systematic use is made of the faithful representations of the three Lie algebras by 4 × 4 matrices: A₃ = sl(4,C), C₂ = sp(4,C), D₂ = o(4,C). The inclusions sl(4,C) É sp(4,C) and sl(4,C) É o(4,C) are important in our presentation, since they allow to employ one of the methods which considerably simplifies the calculations when finding the fine group gradings of the subalgebras sp(4,C) and o(4,C).
issn 1815-0659
url https://nasplib.isofts.kiev.ua/handle/123456789/149045
citation_txt Fine Gradings of Low-Rank Complex Lie Algebras and of Their Real Forms / M. Svobodová // Symmetry, Integrability and Geometry: Methods and Applications. — 2008. — Т. 4. — Бібліогр.: 26 назв. — англ.
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first_indexed 2025-12-07T13:33:06Z
last_indexed 2025-12-07T13:33:06Z
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