Special pure gradings on simple Lie algebras of types $E_6$, $E_7$, $E_8$

Fuente: arXiv
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Main Authors: Draper, Cristina, Elduque, Alberto, Kochetov, Mikhail
Format: Preprint
Published: 2025
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author Draper, Cristina
Elduque, Alberto
Kochetov, Mikhail
author_facet Draper, Cristina
Elduque, Alberto
Kochetov, Mikhail
contents A group grading on a semisimple Lie algebra over an algebraically closed field of characteristic zero is special if its identity component is zero; it is pure if at least one of its components, other than the identity component, contains a Cartan subalgebra. We classify special pure gradings on Lie algebras of types $E_6$, $E_7$, $E_8$ up to equivalence and up to isomorphism. To this end, we use quadratic forms over the field of two elements to show that there are exactly three equivalence classes for $E_6$, four for $E_7$, and five for $E_8$. The computation of the corresponding Weyl groups and their actions on the universal groups yields a set of invariants that allow us to distinguish the isomorphism classes.
format Preprint
id arxiv_https___arxiv_org_abs_2507_03762
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Special pure gradings on simple Lie algebras of types $E_6$, $E_7$, $E_8$
Draper, Cristina
Elduque, Alberto
Kochetov, Mikhail
Rings and Algebras
17B70
A group grading on a semisimple Lie algebra over an algebraically closed field of characteristic zero is special if its identity component is zero; it is pure if at least one of its components, other than the identity component, contains a Cartan subalgebra. We classify special pure gradings on Lie algebras of types $E_6$, $E_7$, $E_8$ up to equivalence and up to isomorphism. To this end, we use quadratic forms over the field of two elements to show that there are exactly three equivalence classes for $E_6$, four for $E_7$, and five for $E_8$. The computation of the corresponding Weyl groups and their actions on the universal groups yields a set of invariants that allow us to distinguish the isomorphism classes.
title Special pure gradings on simple Lie algebras of types $E_6$, $E_7$, $E_8$
topic Rings and Algebras
17B70
url https://arxiv.org/abs/2507.03762